
Qass. 
Book. 



/ 



-- '' 



^ 



u 



PRODUCTIVE FARMING 



V 



A FAMILIAR DIGEST OF THE RECENT DISCOVERIES OF LIEBIG, 
JOHNSTON, DAVY, AND OTHER CELEBRATED WRITERS ON 
/ VEGETABLE CHEMISTRY; SHOWING HOW THE RESULTS 
OF TILLAGE MIGHT BE GREATLY AUGMENTED. 



BY JOSEPH A. S: 




NEW Y|5wK: ^ 
ON & C^^^^OO BRO 



D. APPLETON & C^TT^OO BROADWAY 
PHILADELPHIA: 

GEO. S, APPLETON, 148 CHESNUT STREET. 
1843. 

L . I'. 









JOHN F. TROW, PRIISTER, 
33 Ann-street, 



5- 



By Traiisfor ^ 

Dept. of Agrtctdttire ^ 

OCT 1? 1840 Y. 



PRODUCTIVE FARMING 



CONTENTS 



CHAPTER I. 

Page 
Introductory Observations, 9 

CHAPTER n. 

Some Account of the Simple or Elementary Bodies found 

(combined or uncombined) in Animals, Plants, and Soils, - 23 

CHAPTER ni. 

Plants and Animals are both alike endowed with Life ; the 

Elementary Materials and many of the Proximate Principles • 

of Animal and Vegetable matter are precisely identical — 
they have similar Organs essential to their growth and re- 
production, and are nourished or destroyed by the same 
agencies, 33 

CHAPTER IV. 

Of the Elementary Composition of Water ; of the Composi- 
tion of the Atmosphere; and of the artificial Application of 
Water to Grass Lands, 55 

CHAPTER V. 

Of the Nature of Vegetable Growth ; the true use of Vege- 
table Mould or Humus; and of the Sources of the Element- 
ary Constituents of Plants, 60 

CHAPTER VI. 

Of the Sources of the Saline, Earthy, and other Unorganized 

Constituents of Vegetables, 81 

CHAPTER VII. 

Of the necessary Relation between the Composition of a Soil 
and the Vegetables it is fitted to raise. Fallowing and 
Green Crops considered as Vegetable Manure, - - - 86 



CONTENTS. 



CHAPTER VIII. 

Of the Nature and correct Use of the Excrements of Animals 
considered as Manure ; the Mode of its Action and Preser- 
vation. — Bone Dust, and dead Animal Matter, - - - 97 

CHAPTER IX. 

Of the comparative Value of Vegetable Manure, as contrasted 

with Animal Excrements, ------- 116 

CHAPTER X. 

Of Manures of Mineral Origin, or Fossil and Artificial or 
Chemical Manures ; their Preparation, and the Manner in 
which they act. — Of Lime in its dift'erent States ; its Opera- 
tion as a Manure. — Of Alkalies and Common Salt, as to 
their Action upon the Land, ----- . 119 

CHAPTER XI. 

jOf the Composition of Productive Soils, and of the Agency 
of the Elements in their Natural Formation from the Rocks 
upon which they rest, • 129 

CHAPTER XII. 

Of the Chemical Analysis of Soils, and how far this is practi- 
cable by tlie Farmer, 143 

CHAPTER XIII. 
Of Advertised " Fertilizers" for the Soil, - . • - 148 



PREFACE. 



This book is a compilation. The object of its com- 
piler has been the simplification of the more strictly- 
scientific and technical writings of the principal agricul- 
tural writers of the present age. Practical farmers 
require the simplest and most elementary statements. 
The position of the agricultural interest renders it de- 
sirable that the recent views of Professor Liebig, the 
distinguished chemist, who has effected a complete revo- 
lution in the physiology of vegetation, should be pre- 
sented in a style free from difficulty, condensed and 
separated from such portions of his work as would only 
bewilder ordinary readers. How far the attempt may 
be successful, the world must judge. The published lec- 
tures of the late Sir Humphrey Davy have been freely 
cited, and such portions selected, as, while they do not 
clash with later discovery, may prove a useful addition. 
The writings of Mr. Johnston, whose little elementary 
book is well known, have been laid under contribution, 
as well as the lectures of Dr. Mason Good ; and such 
useful statements as have appeared at various periods in 
periodicals devoted to the furtherance of agricultural 
science. It is to be hoped, that without torturing the 
sense of previous writers, nothing will be found in these 



b PREFACE. 

pages inconsistent with the doctrines of the learned Ger- 
man professor, whose writings, though admirably adapted 
for the perusal of those who are familiar with chemistry 
and physiology, are susceptible of being abridged and pre- 
sented to the industrious farmer in a form less repulsive, 
because less learned, and consequently, more generally 
intelligible. 




MODERN AGEICULTUUE 



CHAPTER I. 

Introductory Observations. 



Agricultural Science has for its objects all those 
changes in the arrangements of matter connected with the 
growth and nourishment of plants, the constitution of soils, 
the manner in which lands are enriched by manure, or ren- 
dered fertile by the different processes of cultivation; and 
no rational system of farming can be formed without the 
practical application of well-understood scientific princi- 
ples. Such a system must be based on an exact acquaint- 
ance with the means of nutrition in vegetables, with the 
influence of soils, and the action of fertilizing materials 
upon them. The object of the farmer is, to raise from a 
given extent of land the largest quantity of the most valu- 
able produce at the least cost, with the least permanent 
injury to the soil ; and the sciences of chemistry and geology 
throw light on every step he takes, or ought to take, in 
order to effect this main object. Whoever reasons upon 
agriculture is obliged continually to recur to these sciences. 
He feels that, without such knowledge, it is scarcely pos- 
sible to advance one step ; and, if he be satisfied with 
insufficient views, it is not because he prefers them to accu- 
rate knowledge, but generally because they are more cur- 
rent. It has been said, and undoubtedly with great truth, 
that a philosopher would most probably make a very un- 
profitable business of farming ; and this, certainly, would 
be the case if he were a mere philosopher. But there is 
2 



10 PRODUCTIVE FARMING. 

good reason to believe, that he would be a more successful 
aj^riculturist than a person equally ignorant of farming, but 
ignorant of chemistry altogether: his science, as far as it 
"Went, would be useful to him. The great purpose of 
chemical investigation in agriculture ought, undoubtedly, 
to be the discovery of improved methods of cultivation ; 
but to this end, not only practical knowledge but general 
scientific principles are alike necessary; nor is industry 
ever so efficacious as when directed by science ; as he 
who, journeying in the night, aided by the most intelligible 
directions as to the way, is more certain of his footsteps if 
he carry a lamp to explore his path. Science cannot long 
be despised by any persons as the mere speculation of 
theorists, but must soon be considered, by all ranks of men, 
in its true point of view, — as the refinement of common 
sense, guided by experience, gradually substituting sound 
and rational principles for vague popular prejudices. If 
land be comparatively unproductive, the sure method of 
determining the cause is, first to ascertain the exact nature 
and relative quantities of the ingredients which form the 
soil, (which can only be done by chemical analysis,) and 
then to supply such soil with the deficient materials requi- 
site for the growth of such vegetables as it is best fitted to 
raise. The preparation of compost will only be of real 
use when materials, which do not afiford singly an efficient 
or convenient manure, are made to do so by their mixture. 
Every farmer has it in his power so to compound the best 
from his store of manuring materials, that the defects of 
his soil may not only be remedied, but that the crops may 
receive those substances in sufficient quantity which are 
required for their vigorous growth. To do this, however, 
it is requisite to know not only the component parts of the 
soil, but also those of the crops. If these are not taken 
into account, no clear idea either of the composition, much 
less of the action of manure, will ever be obtained ; and 
many substances of real value will be tried, and, from mis- 
application, tend to useless, if not injurious results. Per- 
haps iron may be found in injurious excess, which may be 



PRODUCTIVE FARMING. 11 

rendered harmless by the addition of lime ; or an excess 
of sand may be neutralized by the addition of clay. Is 
there a deficiency of lime 7 The remedy is obvious ; or an 
excess of undecomposed vegetable matter may be removed 
by the judicious use of lime, by paring and burning. With 
the aid of chemistry, the precise value of any variety of 
limestone may be determined in a few minutes ; and so its 
fitness or unfitness, as one among many substances intended 
to fertilize the soil, may be determined by a less expensive 
experiment than waiting to observe its action upon the 
land. In the same way, peat earth of a certain consistence 
and composition is an excellent manure; but there are 
some varieties of peat which contain so large a quantity of 
iron as to be absolutely injurious, if not destructive to corn 
and grasses. Now, nothing can be more necessary, more 
useful, and fortunately more simple, than the mode of de- 
termining whether a metallic substance be present. More 
especially, it is solely by a reference to the elementary 
principles of chemistry, and the ascertained constitution of 
manures, vegetables, and the air and soil in which they 
live and thrive, that we can determine whether it is wiser 
to plough that manure into the land, to apply it in a fresh, 
or in a fermented and decomposing state. We know, 
that soon as dung begins to decompose, it throws off its 
volatile or gaseous parts. It is necessary that what is thus 
lost should be examined. It may be (which is the fact) 
that such evaporation is not only the escape, but the actual 
loss of that which forms a most material ingredient in the 
food of plants : and so, whether this shall be supplied 
gradually to the growing vegetable, or suddenly, is a tan- 
tamount question in the mind of an intelligent agriculturist 
to the inquiry often agitated among practical farmers, and 
determined only by individual caprice or fancy, as to 
whether the produce of the stable or the farm-yard is best, 
when spread upon the soil in a fresh or in a putrid state. 
When, for instance, it is considered, that with every pound 
of the strongly-pungent smelling ammonia lost in the air, 
a loss of at least sixty pounds of corn must correspondingly 



12 PRODUCTIVE FARMING. 

be sustained, — and that with every pound of urine a pound 
of wheat might be produced, — not only must we feel sur- 
prise at the ignorance which prevails as to the fact, but 
equally so at the indifference manifested by those who are 
aware of the value of such manure as to the best mode of 
applying it. On some soils a plant will thrive, on others 
it will sicken ; and the same knowledge which will enable 
us to correct a faulty or weak vegetation, will enable us also 
to produce far more abundant results than occur under the 
most favourable ordinary and natural circumstances. Agri- 
culture has hitherto never fairly sought aid from that sci- 
ence which is based on the knowledge of those substances 
which plants extract from the soil, and of those restored 
to the soil on which they grow by means of manure. The 
application of such principles will be the task of a future 
generation ; for what can be expected from the present, 
which recoils with seeming distrust and aversion from all 
the means of assistance offiered by chemical investigation ? 
A future generation will derive incalculable advantage from 
these means of help, and make a rational use of philosoph- 
ical discoveries. Here a marked and wide difference ex- 
ists between the progress of manufacture and the history 
of agricultural operations. We see the steam-engine mul- 
tiply indefinitely the labour of the human hand — supersede 
and almost infinitely exceed the united power of brute 
exertion; invention has lacked no mechanism to produce 
myriads upon myriads of the same fabric ; thousands of 
piles of manufactured silks and cottons are produced annu- 
ally, one factory supplying daily as many yards as would 
encircle the globe — strange advancement on the ancient 
spinning-wheel ; while the sons of the soil still toil on 
through the long summer months, and brave the winter's 
cold, to reap the same quantity of produce from the soil as 
their forefathers of a thousand years ago. We do not say 
that there is no limit to the capabilities of the earth's sur- 
face, but fearlessly maintain that such limit is yet far from 
realization ; and that not until prejudice be silent, and in- 
teUigence more universal, can it be hoped that the broad 



PRODUCTIVE FARMING. 13 

acres of our island home will yield to science and skill all 
the treasures they contain. 

At a recent meeting of one of the Irish agricultural 
associations, a Scottish agriculturist is reported to have 
said, among other things, that " If science were permitted 
to do for farming all of which science is capable, the cla- 
mour about repeal of the Corn Laws would soon cease, 
and the prospect of starvation before us would vanish." 
He observed, that " Great Britain, besides supplying her 
own population with food in abundance, would become an 
exporting country for ages to come : that unless a more 
rational system of farming be adopted throughout the 
country, we shall have want, and its offspring, crime, at 
our doors and on every side of us. The manufacturers 
are offering premiums on the increase of population. That 
population is increasing far beyond the supply of food ne- 
cessary for it, [he might have added, at the rate of a 
thousand a day, while the surface of our island remains the 
same ;] and unless the government, or the great agricultu- 
ral societies, take the matter in hand, and that speedily, we 
shall soon feel that, solely from lack of food for her manu- 
facturing population, the greatness of this empire, so long 
the wonder and envy of the world, will become a thing to 
be talked of as a tale that has passed away." 

Haifa century sufficed to Europeans, not only to equal, 
but to surpass the Chinese in the arts and manufactures; 
and this was owing merely to the application of correct 
principles deduced from the study of chemistry. But how 
infinitely inferior is the agriculture of Europe, even of 
boasted England, to that of China! The Chinese are the 
most admirable gardeners and trainers of plants, for each of 
which they understand how to prepare and apply the best 
adapted manure. Their agriculture is the most perfect in 
the world : and there, where the climate in the most fertile 
districts differs little from the European, very little value 
is attached to the excrements of animals. Patient obser- 
vation of results, and a ready adoption of really useful 
plans ; steady persistence, not in antiquated methods and 



14 PRODUCTIVE FARMING. 

notions, but in all that has been found by experience to be 
beneficial, — has raised the agriculture of that country, long 
ago, to a position which would rapidly, nay, instantly, be 
ours, if science were permitted to achieve for us that 
which, with them, has been the slow growth of centuries of 
experiment. 

The soil of England offers inexhaustible resources, 
which, when properly appreciated and employed, must 
increase our wealth, our population, and our physical 
strength. The same energy of character, the same ex- 
tent of resources which have always distinguished Eng- 
lishmen, and made them excel in arms, commerce and 
learning, only require to be strongly directed to agriculture, 
to ensure the happiest effects. We possess advantages in 
the use of machinery and the division of labour, peculiar 
to ourselves ; and these having been mainly instrumental in 
aiding one great division of human industry, we are justi- 
fied in the assertion, that the steam-engine and machinery 
has not done more for trade, than science and skill, in 
various ways, may do for land. Although it is obvious to 
all reflecting persons, that machinery, which is science in 
another form, is a good thing, we cannot wonder if we find 
some ready to say, " I know it is a bad thing, for it de- 
prived me of employment." To attempt to convince such 
a man would be difficult. It would be useless to argue 
with that man, that a number of individuals had gained, 
though he was a loser. His loss is to him evident ; and 
the gain spread over a vast surface of society is an argu- 
ment which makes no impression upon him. 

Besides chemistry, there is another science which has 
many relations to practical farming — the science of geolo- 
gy, or that which embodies all ascertained facts in regard 
to the nature and internal structure, both physical and 
chemical, of the solid surface of our globe. Though the 
substances of which soils chiefly consist are so few in number, 
yet every practical man knows how very diversified they are 
in character, how very different in value. Thus, in some 
of the southern Enghsh counties we have a white soil, con- 



PRODUCTIVE FARMING. 15 

sisting, apparently, of little more than chalk ; in the cen- 
tral part of the country, a wide plain of dark-red land ; in 
the border counties of Wales, and on many of our coal fields, 
tracts of country almost perfectly black; while yellow, 
white and brown lands give the prevailing character to the 
soils of other districts. These differences arise from the 
varying proportions in w^hich the sand, lime, clay, and iron 
which colour the soils have been mixed together. Now, 
geology explains the cause why they have been so mixed 
in different parts of the country — by what natural agency, 
and for what end ; and by its aid we can predict the gene- 
ral quality of the surface-soil, and, more than this, of the 
unseen sub-soil in the several parts of entire kingdoms. 
We may learn, if the soil be of inferior quality, and yet 
susceptible of improvement, whether the means of improv- 
ing it are likely, in any given locality, to be attainable at 
a reasonable cost. 

Whether we attempt to investigate the composition of 
natural bodies, or, confining our attention to the review of 
those general diversities so remarkable on the earth's sur- 
face, the division of them all into two grand classes, as 
simple or compound, is an essential preliminary to a cor- 
rect comprehension of the subject. Those substances are 
simple, which cannot, by any known method, be separated, 
decomposed, or divided, in such a manner as to produce 
particles different in their properties from one another. On 
the other hand, those substances are compound which, by 
experiment, maybe resolved into particles of an unlike na- 
ture. Thus, marble is a compound body ; for by a strong 
heat it is converted into lime— an elastic fluid, which is 
carbonic acid gas, (itself also a compound,) being disen- 
gaged during the process. Vegetable substances, whether 
in their living or dead state, are mostly of a very compound 
nature, and consist of a great number of elements. For a 
period of many centuries, and even till a very late date, 
there were four substances held to be elementary, or sim- 
ple. These were Fire, Air, Earth, and Water. Nobody 
could prove them so ; and yet, of these four bodies, all 



16 PRODUCTIVE FARMING. 

others in nature were supposed to be constituted. This 
system continued to be orthodox till very lately, when three 
of these imaginary elements, namely, Air, Water, and 
Earth, were proved to be compounds ; and, as we shall see 
in the progress of this work, a correct understanding of the 
properties of the atmosphere, and of its relative agency over 
vegetation, is indispensable to the adoption of such plans 
as are intended to increase the fertility of the soil. As to 
fire, it is still unknown whether it be simple or compound, 
in what its essence consists, or by what causes its effects 
are produced. The study of temperature, of the relative 
dryness or moisture of the air, of the action of the sun's 
hewt over soils and vegetation, is closely identified with the 
science of agriculture. The influence of the changes of 
seasons and of the position of the sun on the phenomena of 
vegetation, demonstrates the effects of heat on the functions 
of plants. The matter absorbed from the soil can only 
enter the roots in a fluid state ; and when the surface is 
frozen, this mode of communication is suspended. The ac- 
tivity of chemical changes in living vegetables is likewise 
increased by a certain increase of temperature, as is evident 
if a stalk of henbane be partially immersed in hot water : 
its leaves will, for a time, become erect, and quickly forego 
their drooping arrangement, evidently referable to the in- 
creased rapidity with which fluids, under such circum- 
stances, rise in the minute vessels of the vegetable. Heat, 
then, is rather to be regarded as an agency by which both 
compound and simple substances are alike affected. What 
the ancients considered to be simple bodies, are no longer 
considered to be such : but, in place of these four assumed 
substances, the chemists of modern times have elevated to 
the dignity of elements, or simple bodies, a far more nume- 
rous race. No one, however, asserts now-a-days, that even 
these are all absolutely simple. The term " element," in- 
timates no more than that the body to which it is applied 
has never, in the opinion of modern chemists, been subject 
to further d vision or decomposition : that it has never been 
divided into particles, different from one another, or from 



PRODUCTIVE FARMING. 17 

the original substance. The number of simple, or elemen- 
tary substances, at present known, and constituting visible 
Nature around us, xs fifty-four. 

Now, if these elementary, or simple substances are 
placed either artificially, or, as they are presented in the 
universe, naturally in contact with each other, they com- 
bine, or refuse to combine ; and by such combination, when 
it occurs, a great variety of compound substances are pro- 
duced. Some combinations are effected instantly, some 
more slowly and with difficulty, and there are certain ele- 
ments which can scarcely, by any means, be made to com- 
bine. The compounds produced by such combinations 
possess properties very different from those of the sepa- 
rate elements of which they are composed. Thus, carbonic 
acid, or the gas which sparkles in fermented liquors, com- 
bines very readily with pure caustic lime, and the product 
of the union is common chalk. So, if the proportions be 
varied, the same two elements produce the common air we 
breathe and the strongest aquafortis or nitric acid. The 
power, in virtue of which simple bodies can combine and 
produce compounds, is one of which the nature is totally 
unknown. Chemists have learned no more than that sim- 
ple bodies, or bodies supposed to be simple, do combine ; 
but WHY they combine, or W'hat that is which makes them 
combine, they have not discovered. To the illustrious 
Dalton belongs the discovery that they do not unite at 
random, but always in definite proportions of each; so 
that, if the elements be represented by numbers, the pro- 
portions in which they unite may be expressed either by 
those numbers, or by some simple multiples of them. Thus, 
sugar and Indian rubber are compounds resolvable into 
precisely the same ultimate elements, only in different pro- 
portions ; and, as the following table will illustrate, nearly 
one half the weight of all vegetable productions which are 
gathered for food for man or beast, in their dry state, are 
but varying compounds of the same elementary or simple 
bodies, the names of which are appended over the an- 
nexed numbers. What the properties of these elements 



18 PRODUCTIVE FARMING. 

in their separate state may be, is not our immediate pur- 
pose. 

Carbon. Hydrogen. Oxygen Nitrogen. Ash. 

Hay, .... 458 50 387 15 90 

Potatoes, . . 441 58 439 12 50 

Wheat straw, 485 52 389 4 70 

Oats, .... 507 64 367 22 40 

parts by weight in 1000 pounds of each of the above veg- 
etable substances. 

If we take the ash left by a known w^eight of wheat 
straw, or of hay, and mix it with the proper quantities of 
the four elementary substances named in the foregoing ta- 
ble, we shall certainly be unable, by this process, to lorm 
either the one or the other. The elements, therefore, into 
which all vegetable compounds are ultimately resolvable, 
are not merely mixed together; they are united in some 
closer and more intimate manner. To this more intimate 
state of union the term chemical combination is correctly 
applied. Again, woody fibre, gum, sap, and the various 
fluids and substances which form a plant, are themselves 
mostly resolvable into varying proportions of the same ulti- 
mate elements, which, taken together form the entire vege- 
table. Thus, sugar forms one of the proximate principles 
of the sugar cane, and India rubber is one of the proxi- 
mate principles of a South American tree, which contains 
no sugar ; yet sugar and India rubber are essentially com- 
posed of the same materials. So, if charcoal be burned in 
the open air, it slowly disappears, and forms a kind of air 
or gas, known by the name of carbonic acid, an elastic 
fluid precisely identical with that which forms the froth in 
ginger beer or common yeast. Now^, this carbonic acid is 
formed by the union of the charcoal or carbon, while burn- 
ing, with one of the elements composing common air, 
named oxygen; and in this new form, the elements carbon 
and oxygen are said to be chemically combined. Again, 
if certain vegetable and animal materials are mixed to- 
gether, and left to the agency of the atmosphere, they re- 



PRODUCTIVE FARMING. 19 

act upon each other — perhaps become heated, as happens 
in a heap of stable dung, and are said to become decomposed. 
New compounds are formed from the union of previously 
existing elements; perhaps ammonia is one of the most com- 
mon and obvious, as indicated by its effect upon our eyes 
and nostrils. This, then, is as purely a chemical process as 
the conversion of wood into vinegar, or into charcoal, or 
the change that occurs when the flour of grain is convert- 
ed by the distiller into ardent spirits ; and in all well-direct- 
ed attempts to fertilize the soil, a knowledge of these 
changes is absolutely necessary : at least, he who proceeds 
without it has disappointment in prospect, and gropes in 
the dark, with uncertainty for his guide. 

Now, chemical affinity is not only evident in the changes 
which masses of dead inorganic matter produce upon each 
other: it is found to be actively at work in the phenomena 
of vegetation ; thus proving that the growth of plants is 
more completely a chemical process than might have been 
imagined : and, as our further illustrations will tend to 
prove, the same law of affinity is equally operative upon 
animal structure, which, like that of plants, is not more 
truly alive than they. The sap consists of a number of in- 
gredients dissolved in water by chemical attraction ; and 
it appears to be in consequence of the operation of this 
power, that certain principles derived from the sap are 
united to the vegetable organs. By the laws of chemical 
attraction, different products of vegetation are changed and 
formed during the process of growth : vegetable and ani- 
mal remains are decomposed by the action of air and water 
or exert upon those fluids a mutual agency essential to the 
change ; rocks are broken down and converted into soils, 
and soils are more finely divided and fitted as receptacles 
for the roots of plants. The repulsive energy of solar heat 
or of that generated during chemical changes of constant 
occurrence, serves as the only counterbalance to that at' 
traction which pervades the particles of all living or dead 
matter : and thus the harmonious circle of growth and de- 
cay is produced by their mutual operations. The difl^erent 



20 PRODUCTIVE FARMING. 

influence of the different solar rays on vegetation is but 
partially understood. There are rays transmitted from ihe 
sun which do not impart light, and which yet produce more 
heat than the visible rays. The effect of these invisible rays 
is purely chemical and independent of the heat they pro- 
duce. Thus, potatoes, which sprout in a comparatively 
dark cellar, send out nearly colourless shoots. Plants kept 
in the dark in a hot-house, grow luxuriantly, but never 
acquire their natural colours ; their leaves are white or 
pale, and their juices watery and sweet. So the upper 
surface of most leaves is darker than the lower, upon the 
same principle that the belly of a fish is whiter than its 
back. 

The most obvious instance of Electrical Agency in ex- 
ternal nature occurs in thunder and lightning. Electrical 
changes are of constant occurrence ; but as yet the effects 
of this power, not as accidental, but as essential to healthy 
vegetation, have not been correctly estimated. No doubt 
the germination of seeds, as well as the growth of plants, 
is materially modified by the peculiar electrical condition 
of the earth and the atmosphere, and by the varying state 
of each. It is known that corn will sprout more rapidly 
and readily in water positively electrified — that is, charged 
with electricity in excess or beyond its natural quantity ; 
and that if, by artificial means, water be deprived of its 
natural amount of electricity, its power of stimulating the 
growth of seeds is thereby diminished. Experiments made 
upon the atmosphere show that clouds are usually deficient 
of electricity ; and as when a cloud is in one state of elec- 
tricity, the surface of the earth beneath that cloud is 
brought into the opposite state, it is probable that, in com- 
mon cases, the surface of the earth is charged with the 
electric fluid in excess. 

We have spoken of Chemical affinity : it is sometimes 
well named Elective or Chemical attraction, in as much as 
it is but an exemplification of one form of that law which 
maintains the order of the universe. It is the expression of 
the fact, that certain elements of unlike nature combine 



PRODUCTIVE FARMING. 21 

with each other when placed in contact, or (figuratively 
speaking) refuse to combine with any other, electing even 
the proportions in which only such combinations can occur. 
This affinity is but one division of the great law of attraC' 
Hon. In this aspect, there are Jive forms in which the re- 
lations of all bodies to each other may be arranged. We 
begin with that which compels the heavenly bodies to 
rotate round the sun ; or a stone when thrown upwards to 
fall to the ground — in other words, to gravitate towards 
the earth's centre. Next, there is the attraction of cohe- 
sion : thus, particles of oil will rise through water, and 
having reached the ransje of each other's attraction, will 
unite into one common and separate body. It is this form 
of attraction which gives roundness to the drops of dew, or 
of the rain as it falls, and is the sole cause of the arched 
form of the rainbow. In the same way, drops of water or 
of quicksilver placed upon a dry plate, have a tendency to 
unite, not only when they touch, but to run together when 
placed near each other. So, perfectly smooth and polished 
plates of glass or metal have a strong tendency to cohere. 
It is by the same means that the great number of rocks 
seem to be produced that enter into the substance of the 
earth's solid crust. The lowermost rocks are united by an 
intimate crystallization which is the most perfect form of 
cohesive or aggregate attraction that can exist among the 
particles of solid bodies. The next form of attraction is 
observed as occurring between bodies unlike in their na- 
ture, solids and fluids, capillary attraction, as when sap 
rises in the minute vessels forming the stem of a tree against 
its own weight, or in other language, overcoming the at- 
traction of gravitation downwards. The Latin word which 
signifies a hair, is used in this instance to form the word 
denoting the extreme tenuity and delicacy of these narrow 
vessels, as only in such could fluids rise : hence the reason 
and the wisdom of this arrangement. 

Electrical and Magnetic attraction are important sub- 
jects for study, to which in a practical work it is not neces- 
sary very minutely to allude. It is well ascertained that 



22 



PRODUCTIVE FARMING. 



the thorns, spines, or prickles that exist on a variety of 
plants serve not merely for their defence ; they have a re- 
lation to the electrical condition of the atmosphere ; cases 
having been recorded in which spines have grown more 
than an inch during a thunder-storm. Some of the acacia 
tribe are fretted over with formidable spines which will 
take off a charge of electricity from a prime conductor as 
rapidly as a brass point— doubtlessly from the presence of 
a metal in those spines, probably the metallic base of flint. 
Now it is very unlikely that only the prickly plants require 
the electric stimulus. We know that, though the torpedo 
and electrical eel have power to benumb and kill, yet hu- 
man beings, who have no such powers in health and in 
disease, are always charged with varying quantities of the 
electric fluid. So also of all vegetables : oat and wheat 
straw contain silica, which is metallic ; and the firmness 
of the stem may not be, and is not, the only reason for its 
presence. Lastly, we have Chemical attraction or affinity. 
A few instances of its operation have been already noted ; 
but some affinities are more powerful than others. Pure 
lime has a strong affinity for carbonic acid gas, and this is 
a wise ordination ; and it is equally a proof of design that 
it should form one of the ingredients of the atmosphere. 
Under this arrangement of things, whole mountains of lime 
have been crumbled during successive ages into fertile beds 
of chalk. But lime has a still greater affinity for sulphmic 
acid or oil of vitriol than it has for carbonic acid ; and so, 
if natural or artificial chalk be subjected to the action of 
vitriol, another decomposition ensues : the carbonic acid 
flies off, leaving the lime to combine with the acid for 
which it has a more powerful aflSnity, the result of the new 
union being sulphate of lime, better known as alabaster or 
common gypsum. These transformations may not only be 
produced artificially, but are of constant occurrence, though 
of slow operation, in the great laboratory of Nature. To 
understand them is essential to the slightest knowledge of 
those chemical changes w^hich are identical with the pro- 
cesses of growth in the vegetable world, and indeed in all 



PRODUCTIVE FARMING. 23 

living organized bodies,— and there are sufficient motives 
connected both with pleasure and profit to er^ourage inge- 
nious men to pursue this new path of investigation. 



CHAPTER II 



Some Account of the Simple or Elementary Bodies found (combined 
or uncombined) in Animals, Plants, and Soils. 

It is absolutely necessary, in order to a right appre- 
hension of the changes that occur during vegetable growth, 
and, of course, to a correct estimation of the most rational 
methods of forcing or favouring healthy vegetation, that 
we should become familiar with some of the most common 
properties of those simple bodies or elements, of which all 
nature around us is compounded. 

Four of them, by combining with other simple bodies 
that will burn, form acids ; eight of them are inflammable; 
and there are upwards of forty metals. 

First, let us speak of Oxygen. Oxygen, in union with 
latent heat, forms Oxygen gas, constituting about one-fifth 
of the air of our atmosphere. It is an elastic fluid at all 
known temperatures. It is heavier than the air, and sup- 
ports combustion with much more vividness than common 
air ; so that if a small steel wire, or a watch spring, having 
a bit of burning wood attached to it, — or, better still, a 
bit of phosphorus or brimstone, be introduced into a bottle 
filled with this gas, it burns with surprising splendour. 
Oxygen is a substance very extensively diflfused throughout 
the material world: it forms with nitrogen the air we 
breathe; united with another element, named hydrogen, it 
forms water. It exists as a constituent of all animal and 
vegetable matter; and is found also naturally in combina- 



24 PRODUCTIVE FARMING. 

tion with most mineral productions; from some of which, 
for experimental purposes, it may with great ease be pre- 
pared. Oxygen gas, when suddenly compressed, evolves 
both light and heat ; is sparingly dissolved by water, 100 
cubic inches taking up only three or four of the gas. If a 
mouse, or a bird, were confined under a large bell-glass, 
filled with common air, it would live until it had consumed all 
the oxygen contained in that portion of air, and no longer. 
If, instead of the bird, a bit of burning brimstone, or a can- 
dle were placed there, it would burn until it had absorbed 
all the oxygen, and then become extinguished. 

2i Hydrogen. — Hydrogen, or inflammable air, is the 
lightest known substance, being about sixteen times lighter 
than common air. For this reason, it is used in filling 
balloons. The common gas in the streets and shops 
is mostly used for this purpose, instead of pure hydrogen ; 
the carbon it contains not materially destroying its light- 
ness. Not only is pure hydrogen the lightest of gases, 
but it is highly inflammable ; it W'ill neither support com- 
bustion nor respiration ; in other words, if a lighted taper 
or a living animal be immersed in pure hydrogen gas, it 
would cease to burn, or die. Hydrogen and oxygen are 
the two elements w'hich form pure water, of which we must 
say more in another place. When these gases are mixed 
in certain proportions, they unite and explode with great 
violence if a lighted candle be brought in contact with 
them ; for experiment' sake, one part of hydrogen, and six 
of oxygen or even atmospheric air, w^ill form a very power- 
ful explosive mixture. When a stream of hydrogen gas 
issuing from one vessel, and a jet of oxygen from another, 
are made to inflame as they unite, a most intense heat will 
be generated, sufficient to melt the clay of a common to- 
bacco pipe, and render lime perfectly fluid. Neither hy- 
drogen nor oxygen are known to occur anywHerein nature 
in any sensible separate quantity. They are abundant 
enough in combination with other matters. 

3. JYitrogen, sometimes called Azote, is another ele- 
mentary substance, entering most largely into the constitu- 



PRODUCTIVE FARMTNG. 25 

tion of universal nature. United with the matter of heat, 
it may be artificially produced and presented as a trans- 
parent, colourless, insipid, incombustible gas, incapable of 
supporting flame or breathing. It may be made to unite 
with oxygen (but of course only in certain definite pro- 
portions) by the agency of electrical fire. It may easily 
be procured by burning a bit of phosphorus in a confined 
portion of air over water. The inflamed phosphorus 
rapidly unites with the oxygen until it has exhausted all 
that the air contains, then combustion stops, and the re- 
maining gas is nearly pure nitrogen. Small creatures 
soon die m it for want of oxygen. It combines in five 
difl^erent proportions with oxygen, forming, in one instance, 
nitric acid or aquafortis; and mixed, rather than chemi- 
cally combined, with one-fifth its bulk of oxygen, it forms 
the air we breathe. Though ammonia is not a simple 
body, and, therefore, not to be classed with the present list, 
it may not be inappropriate, after the mention of hydrogen 
and nitrogen, to say that it results from the union of the 
two. Ammonia exists in rain w^ater, and, as we shall 
subsequently show, is an important auxiliary to vegetable 
growth; it becomes developed in putrid urine or stable 
compost; it is a colourless gas, with a strong pungent 
odour. It dissolves easily in water, and is then called 
hartshorn. It is very volatile; has all the common pro- 
perties of soda and potash, combining readily with acids. 
Sulphate of ammonia exists largely in the soot from coals. 
From this source the " sal ammoniac " of commerce is pro- 
cured. 

Carbon. — Charcoal is the most usual, and best known 
variety of carbon. It is black, soils the fingers, and is 
more or less porous, according to the kind of wood from 
which it has been formed. Coke, obtained by charring, or 
distilling coal, is another variety. It is generally heavier 
or denser than the former, though less pure. Black-lead, 
or carburet of iron, there being in reality no lead in its 
composition, is a third variety, still heavier and more im- 
pure. The diamond is the only form in which carbon oc- 



26 PRODUCTIVE FARMING. 

curs in nature in a state of perfect purity. That the dia- 
mond is essentially the same substance with pure lamp- 
black is a very remarkable circumstance. Charcoal, the 
diamond, lamp-black, and all the other forms of carbon, burn 
away more or less slowly when heated in the air; and, 
combining with the oxygen of the atmosphere, form car- 
bonic acid. 

Oxygen, hydrogen, nitrogen, and carbon, form the ul- 
timate elements into which all the organized part of all 
vegetable and animal substances is resolvable. We say 
organized: bones contain lime, and vegetables contain 
earthy and saline matters; but these are not organized, 
they are deposited in cells, or in a structure so arranged as 
to contain them. 

Chlorine, or Oxymuriatic gas, is, like oxygen gas, a 
permanently elastic fluid. When pure, it has a greenish 
yellow colour, and a very disagreeable odour and acid 
taste. It may not be breathed, and burning bodies are ex- 
tinguished by it. It destroys all vegetable and animal 
colouring substances, as also the effluvium arising from the 
putrefaction of dead animal matter. It does not exist 
separately in nature, but is one of the components of com- 
mon salt. 

Fluorine. — This substance has such strong tendencies 
to combination, that as yet no vessels have been found 
capable of containing it in its pure form. It is one of the 
elements composing the Derbyshire fluor spar or blue John. 
This mineral is a fluate of lime, in other words, a com- 
pound of fluoric acid and lime. Now, fluoric acid is itself 
a compound of fluorine and hydrogen ; and lime is not a 
simple body, but in reality the oxide or rust of a metal 
named Calcium, from the latin word " Calx," signifying 
lime. Fluoric acid may be obtained from the Derbyshire 
spar by the action of sulphuric acid, which combines with 
the lime in consequence of the greater affinity of the two 
than exists between lime and fluoric acid, which by such 
process may be separated. 

Having disposed of these, we proceed to notice (not the 



PRODUCTIVE FARMING. 27 

whole rano^e) but a few other simple substances found in na- 
ture, and chiefly in the animal, vegetable, and mineral world. 

Sulphur. — This is a solid substance, of a lipht yellow 
colour, brittle and tasteless, and when rubbed, emitting a 
peculiar odour. Melted and poured into cylindrical moulds 
it forms the roll brimstone of commerce. It burns with a 
pale blue flame in the open air, during which process it 
combines with the oxygen of the atmosphere, and forms 
sulphuric acid or oil of vitriol. Sulphur is found native in 
Sicily, Italy, and Iceland, and in combination with metals 
and earths in greater or less quantity throughout the min- 
eral kingdom. It is a constituent of many vegetable and 
nearly ail animal structure. 

Phosphorus. — Phosphorus is most easily obtained by 
burning bones to whiteness in an open fire. In this way 
the animal matter is driven off and nearly pure phosphate 
of lime (or a salt composed of phosphoric acid and lime) 
remains. This phosphate of lime, reduced to powder, is 
next mixed with oil of vitriol and water ; decomposition 
ensues in consequence of the greater affinity which oil of 
vitriol or sulphuric acid has for hme than the phosphoric 
acid already in combination with it. Next, by evaporation, 
the addition of powdered charcoal, and exposure of the 
mixed mass to distillation, the liberated phosphorus is sepa- 
rated into its two elements, (phosphorus and oxygen,) the 
former of which distils over, and at a low temperature 
becomes solid. Phosphorus may also be prepared from 
urine. It takes fire at a heat considerably lower than that of 
boiling water. Phosphorus has a w^axy consistence ; when 
burned in oxygen gas, a very dazzling light is produced ; 
and the result of the combination is phosphoric acid, just as 
sulphur or brimstone, burnt in oxygen gas, produces sul- 
phuric acid. Phosphoric acid combined with lime, forms 
phosphateof lime, the solid inorganic constituent of bones. 
Phosphate of lime is easily obtained by exposing bones to 
a red heat in an open fire. Its first action is to blacken the 
bones, converting its animal carbonaceous matter into 
charcoal : if the heat be continued, the charcoal or carbon 



28 PRODUCTIVE FARMING. 

unites with the oxy<ren of the atmosphere in the form of 
carbonic acid gas, and the phosphate of lime remains beau- 
tifully white, left in the shape and arrangement of the 
organized cells it lately filled. Phosphate of lime is found as a 
native mineral production in some parts of Ireland and else- 
where. Phosphorus will dissolve in spirit of wine or in oil, but 
is insoluble in water, under which fluid it is always preserved. 

Iodine. — This simple substance is found existing as an 
undecompounded element in the ashes of marine plants 
after the extraction of the soda they contain. Sea- weed is 
largely used on the coasts of England and Scotland as a 
manure. Iodine is a dark-coloured solid, having somewhat 
the appearanceof black-lead. It unites to all the metals upon 
which its action has been examined, and combines with 
oxygen, forming an acid. 

Next, let us allude to earths and metals, or such forms 
of them as fall within the range of simple elementary 
bodies. We have already said that lime, ordinarily con- 
sidered as an earth, is in reality a metallic oxide ; pure 
soda, pure potash, calcined magnesia, pipe-clay, the base 
of flint, and some other similar substances, are, in truth, 
metals, united to oxygen in the same way as rust of iron is 
a compound of iron and oxygen. Lime, then, or, in chemi- 
cal language, " oxide of calcium," combined with various 
acids, is a very abundant natural production, found widely 
diffused over every part of the habitable globe, as limestone, 
marble, chalk, fluor spar, plaster of Paris, gypsum, or ala- 
baster ; these, under various names, being all of them com- 
pounds of lime with the carbonic, fluoric, or sulphuric acids. 
Besides these, lime, in combination with phosphoric acid, 
enters very largely into the composition of the solid skeleton 
or shell of animals. Pure lime is more soluble in cold than 
in hot water, a fact not without its interest nor intention. 
If chalk be exposed to a red heat, the carbonic acid, one of 
its constituents, is expelled, and pure lime remains. Pure, 
or caustic quicklime corrodes animal and vegetable sub- 
stances, and is never found in them in an unmixed state. 
Lime is one of the most infusible bodies known, but may 



PRODUCTIVE FARMING. 29 

be made to melt by the joint action of the combustion of 
oxygen and hydrogen gases. Lime has a powerful affinity 
for water, and the combination is attended with the extri- 
cation of great heat, as when lime is slaked for the builder. 
In this process the water becomes solid, unites, not mixes, 
with the lime, and in passing from the fluid to the solid state, 
gives out the latent heat necessary to maintain fluidity. 
This heat becoming suddenly sensible, is suflBcient to carry 
off a portion of the water in vapour, the union of the lime 
and the water producing a dry solid. The same chemical 
union occurs when plaster of Paris, or dry sulphate of lime, 
is mixed in certain proportions with water : the fluid solid- 
ifies, and unites with the hme into the hard substance which 
forms the common plaster images or casts hawked about 
the streets by the Italians. Lime combines freely with 
many acids, existing in this form as " muriate of lime" in 
the water of the ocean. Of the application of earthy 
minerals to the land, we will speak in its proper place. 

Sodium. — This is the metallic base of common table or 
rock salt, which is a compound of two elements, chlorine, 
already alluded to, and sodium, with water. The metal 
sodium has a lustre and colour very similar to silver, and is 
so soft as to be pressed into leaves betw^een the fingers. It 
may be obtained through the agency of the galvanic appa- 
ratus. When thrown upon water it decomposes that fluid, it 
soon becomes oxidized, or robs the water of oxygen, setting 
its other constituent, hydrogen, at liberty, the action being 
accompanied with a hissing noise. Chloride of sodium, or 
common salt, is abundantly diffused over the world, both 
as a solid mineral production, and as the principal ingredi- 
ent in sea-water ; it is essential to healthy action, as well 
in vegetable as in animal nutrition. If thrown upon hot 
coals, salt crackles, because the w^ater it contains is not 
chemically combined, but merely mixed or interposed be- 
tween its particles, and so expanding by heat causes the 
separation of those particles and the resulting sound. So- 
dium united to oxygen, forms pure soda ; pure soda united 
to sulphuric acid, forms the Glauber salt, so commonly 



30 PRODUCTIVE FARMING. 

given to cattle ; pure soda united to carbonic acid, forms 
the substance sold in the shops as " soda," and bought for 
the purposes of the washerwoman. 

Potassium, — This is the metallic brise of cgmmon pearl 
ashes. If the pure metal be thrown upon water, like 
sodium it swims on the surface, and darts violently hither 
and thither, with the sudden extrication of flame. This 
flame is burning hydrogen, and the phenomenon arises 
from the great affinity of potassium for oxygen, abstract- 
ing it from water, or all bodies that contain it. If the 
metal potassium be united wnth oxygen, it forms pure, or 
caustic potash, or oxide of potassium ; if pure potash be 
united with carbonic acid, the result is carbonate of potash, 
of which pearl ashes is an impure variety. United with 
nitric acid, potash forms saltpetre, which is found very 
abundantly as a natural product. Potash, combined with 
oxalic acid, is found in sorrel, and other sour plants. Im- 
pure carbonate of potash remains in the ashes of most 
vegetables, and so largely in some of them, as to yield the 
immense supply for trade. Potash, united with fatty or 
oily substances, forms the various kinds of soap. 

Silicon is another metal which, in union with oxygen, 
forms silica, or siliceous earth, existing native in great 
abundance, and forming the chief ingredient m flint, quartz, 
and rock-crystal. From these substances silica may easily be 
obtained, by first heating them to redness, and then throw- 
ing them into water. For all common purposes, sand from 
the glass-house will answer. It unites with potash, and 
forms glass, and is insoluble in all acids, except the fluoric 
acid, for which reason this acid is kept in leaden bottles. 
Silica exists very largely in the hard coating of the sugar 
cane. In the stem of wheat straw, silica is essential to the 
firm, erect position of ^the plant ; consequently, if the soil 
be deficient of silica, (a fact which is easily determined,) 
the ear of corn will droop, upon a slender, short, and lanky 
straw. 

Jlluminium. — This metal, in combination with ogygen, 
forms pure alumina. Alumina, more or less pure, exists as 



PRODUCTIVE FARMING. 31 

a most abundant natural production, being found as a chief 
constituent of clay^ for pottery and bricks. Crystallized, it 
forms those precious gems, the ruby and sapphire : so that 
the difference between a bit of charcoal and a diamond, is 
a similar difference to that which exists between a bit of 
clay and a precious jewel — merely a diversity in the ar- 
rangement of particles of the same matter. 

Barium. — A metal forming the base of the earth baryta, 
and of the various acids in combination with that earth. 
Carbonate of baryta is found native in Derbyshire. Pure 
baryta, like lime, slakes when in contact with water; for 
which it has so strong an affinity, that the heat of a forge 
will not drive it off. 

Magnesium, — The metallic base of the earth magnesia, 
the calcined magnesia of the shops. In combination with 
muriatic acid, it exists largely in sea-water. With sul- 
phuric acid, magnesia forms the common Epsom salt, and 
is found as a native magnesian limestone, in combination 
with lime and carbonic acid. 

Iron. — Iron is found native in many parts of the world, 
and is also very abundant in combination with sulphur, 
and many other substances, such as oxygen, forming ox- 
ides ; also in further union with acids, forming carbonates, 
sulphates, and phosphates. Green copperas is a sulphate 
of iron. Rust of iron, produced by the action of the at- 
mosphere, arises from the combination of the iron with 
oxygen, derived from the air, and also with a portion of 
carbonic acid from the same source, and so may be correctly 
named carbonate of iron. 

Lead. — Metallic lead is rarely found native, but is ob- 
tained in large quantities by smelting the sulphuret, a min- 
eral known by the name of galena. Lead is found also in 
combination with oxygen and acids. 

Copper. — This metal occurs very commonly native in a 
state of perfect purity, sometimes in large masses, at other 
times in a crystalline form. It is commonly found in com- 
bination with sulphur, from which it is generally obtained. 
Blue stone, used by the farrier, is a sulphate of copper. 



32 PRODUCTIVE FARMING. 

Zinc. — Metallic zinc, sometiraes named spelter, is ob- 
tained either from the impure carbonate, a native produc- 
tion called "calamine," or from another natural compound, 
the "sulphuret," or zinc blende. White vitriol used in 
veterinary medicine, is a sulphate of zinc. The ores from 
which it is smelted, exist largely in some districts. — Tin, 
bismuth, antimony, arsenic, nickel, cobalt, and many other 
metallic substances, might similarly be enumerated ; but 
these, existing in comparatively minute quantities, may be 
safely passed over. The elements found in vegetables are 
but few. Oxygen, hydrogen, and carbon, form the great- 
est part of their organized matter. Nitrogen, phosphorus, 
sulphur, manganesura, iron, silicum, calcium, aluminum, 
and magnesium, enter into their composition, or are found 
in the agents to which they are exposed ; and these twelvBy 
out of nearly sixty undecompounded elements, require to be 
familiarly understood by the agricultural chemist. Life 
gives a peculiar character to all its productions : the power 
of attraction and repulsion, combination and decomposi- 
tion, are subservient to it. A few elements, by the diver- 
sity of their arrangement, are made to form the most dif- 
ferent substances; and similar substances are produced 
from compounds which, when superficially examined, ap- 
pear entirely different. 



CHAPTER III. 

Pi.ANTS and Animals are both alike endowed with Life • the Ele- 
mentary Materials and many of the Proximate Principles of Ani. 
mal and Vegetable matter are precisely identical — they have siini- 
lar Organs essential to their growth and reproduction^ and are 
nourished or destroyed by the same agencies. 

If I dig up a stone and remove it from one place to an- 
other, the stone will suffer no alteration by the change of 
place ; but if I dig up a plant, and remove it, strip its 
leaves, and leave the stem standing, or mutilate an animal, 
— that plant or animal will instantly sicken, and perhaps 
die. What is the reason of this ? Both have been per- 
fected in connexion with the same common soil. If I 
break the stone to pieces, though chemically, it may con- 
sist of several elements, yet every individual fragment will 
be found possessed of the original character of the whole 
mass; it is only altered in shape and magnitude; but if I 
tear off a branch from a plant, it will wither and lose the 
properties of its parent stock. The mineral can only be 
destroyed or changed by mechanical or chemical force ; 
while the plant, like all animals, has been produced by 
generation, has grown by nutrition, and been destroyed by 
death, — in fact, it has been actuated by an internal power. 
In what this internal power consists, we know not. Dif- 
ferently modified, we meet with it in both plants and ani- 
mals. Wherever we find it, we denominate it the " prin- 
ciple OF life;" its presence forming a clear distinction and 
boundary between the two great families of animals and 
plants, and all else besides in the universe. A cabbage is 
not less truly alive than the ox which feeds upon it. The 
superiority of the animal over the plant consists chiefly in 
this — the existence of mind or intellect ; and- correspond- 
ingly, a brain and nerves, of which the plant is deficient. 

3 



34 PRODUCTIVE FARMING. 

Now, all living things are said to be organized ; that is, 
made up oi various structures, evidently destined to answer 
certain ends ; and these, taken together, compose the en- 
tire plant or animal : as the root, sap vessels, bark, leaves, 
and other organs of a tree ; and correspondingly, the bones, 
muscles, blood-vessels, skin, and lungs of a horse, a man, 
or of a sheep. But this description is not true of a piece 
of limestone, or a lump of clay, and, therefore, it is said to 
be inorganized. Hence, all the various bodies in nature 
arrange themselves naturally under the two great divisions 
of organized and vital, or inorganized and dead, without a 
single exception. 

In their more perfect forms, the distinctions between an- 
imal and vegetable life are obvious enough. There is a 
wide distinction between a horse chestnut and a chestnut 
horse; but as we approach the contiguous extremities of 
the animal and vegetable kingdoms, the distinction is not 
so easy. There are some natural productions which have 
been originally considered as minerals, afterwards as vege- 
tables, and have at last been regarded as belonging to the 
animal kingdom; less on account of any other property 
they possess than their similarity of chemical and element- 
ary constitution to the well-known ingredients of animal 
matter. Sponges, and many fungous growths, are of this 
character. 

In what part of a plant the living principle chiefly exists, 
or to what quarter it retires during the winter, we know 
not; but we are just as ignorant in relation to animal life. 
In both, it operates towards every point ; it consists in the 
whole, and resides in the whole; and its proof of existence 
is drawn from its resisting those putrefactive or chemical 
agencies which instantly begin to operate as soon as the 
plant or animal is dead. While life exists, a vegetable or 
animal thrives and increases in its bulk ; a tree puts forth 
annually a new progeny of buds, and becomes clothed with 
a beautiful foliage of lungs, (every leaf being in itself a 
distinct lung,) for the respiration of the rising brood, and 
with an harmonious circle of action that can never be too 



PRODUCTIVE FARMING. 35 

much admired, a perpetual supply of nourishment is fur- 
nished first for its own growth, next for the growth and 
perfection of animal life ; while, from its own decay, as 
well as from the death of animal matter, there is formed, 
in rich abundance, the means of new births, new buds, and 
new harvests. In fact, every thing is formed for every thing, 
and subsists, (if we may speak figuratively) by the kind in- 
tercourse of giving and receiving benefits. Such is the 
simple, but beauti ul, circle of nature. That which lives, 
flourishes, decays, and dies, is not lost ; the great principle 
of life only changes its form ; and the destruction of one 
generation of plants or animals is but the necessary requi- 
site to the support or existence of the next. 

Carbonic Acm, Ammonia, and Water, yield elements out 
of which are built up all the organized parts of plants ; 
and it is no less true that these elements form the entire 
organized structure of animals. This being the fact, w^e 
should naturally suppose the conditions essential to the 
growth of each are the same ; in fact, that the food con- 
sumed by vegetables and animals would prove essentially 
similar : and such is actually the case. The process of di- 
gestion in an animal is precisely identical w^ith the process 
of appropriation or nourishment in a plant. Certain inor- 
ganic substances, salts and metallic oxides, serve peculiar 
uses, as lime to give solidity to the bones of an ox ; and 
silica, or the earth of flints, to serve the same end in wheat 
straw. 

We have already spoken of the elementary or ultimate 
constituents of vegetables. Out of these are formed the 
various immediate compounds which are found in them 
The compound substances found in vegetables are, — 1. Al- 
bumen ; 2. Gum; 3. Sugar; 4. Gluten; 5. Woody fibre; 
6. Starch ; 7. Extractive ; 8. Tannin ; 9. Resin ; 10." Wax ; 
11. Fixed and volatile oils ; 12. Bitter principle; 13. Free 
acids ; and a few others ; to which must be added the 
mineral, saline, or metallic substances they contain. 

Out of the same elementary constituents of vegetable 
and animal structure are formed the materials composing 



36 



PRODUCTIVE FARMING. 



the blood and all the secretions — fibrin, gelatin, mucus, al- 
bumen; all the animal acids — spermaceti, hog's lard, train 
oil, and other fatty substances ; ozmazome, urea, sugar of 
milk; together with many other matters enumerated by 
chemists, only some of which are peculiar to the animal 
kingdom ; — so that there is no difference between albumen 
obtained from a vegetable and that which forms, in nearly 
a pure state, the white of an egg. Albumen in a solid 
form constitutes the principal part of the almond, and of 
the kernels of nuts. The juice of a West Indian plant 
{Hibiscus esculentis) contains liquid albumen in such quan- 
tities, that it is employed in Dominica as a substitute for the 
white of eggs in clarifying the juice of the sugar cane. 
Albumen is common to the vegetable as well as the ani- 
mal kingdom, and may be easily distinguished from other 
substances by its property of coagulating or becoming hard 
and permanently solid by the action of moderate heat, or 
of acids. It forms a constituent of the serum of blood, of 
several of the animal secretions, and in a solid form of 
some of the organized structures of the body. Its compo- 
sition, from whatever source it may be obtained, is Carbon, 
52 ; Hydrogen, 7 ; Oxygen, 23 ; and Nitrogen 15 parts, 
(rejecting fractions,) in every 100. 

Let us trace a few more of these comparisons, bearing 
in mind that nitrogen, as one of the elements into which 
both vegetable and animal compounds are ultimately re- 
solvable, exists always in greater proportion in flesh, than 
in grasses. All animal matters do not contain nitrogen ; 
nor are all vegetable substances devoid of it. 

Vegetable gum is analogous to animal mucus. Gum 
is a substance which exudes from certain trees ; it appears 
in the form of a thick fluid, but soon hardens in the air, 
and becomes solid, when it appears white, or yellowish 
white, and somewhat brittle. The characteristic properties 
of gum are its easy solubility in water, and its insolubility 
in spirit of wine. All the varieties of gum are nutricious 
as food. Gum is composed of 43 carbon, 51 oxygen, and 
6 hydrogen, in 100 parts, or nearly. Mucns, a secretion 



PRODUCTIVE FARMING. 37 

found on the surfaces of the lining membrane of the intes- 
tines, possesses the same characters ; and its composition 
is nearly the same. It may be obtained by evaporating the 
saliva to dryness; and is then similar to gum-arabic in its 
general appearance, but rather more opaque. It may be 
procured also by evaporating to dryness the fluid found in 
the shell of the oyster, or water in which that animal has 
been macerated. 

Sugar is essentially the same, whether derived from the 
maple-tree, the sugar-cane, the milk of animals, or even 
from the urine in the disease known by the name diabetes. 
Its composition is 28 carbon, 8 hydrogen, and 64 oxygen, 
in 100 parts, differing not very widely from gum. Sugar 
exists, naturally formed, in many plants and fruits, espe- 
cially the sugar-cane. During the Peninsular war, it was 
larp^ely manufactured from the juice of the beet-root, both 
in France and Germany. It has also been obtained from 
grapes, from manna, from carrots, and from honey. 

Let us compare vegetable gluten w^ith animal gelatin. 
First, of gluten. It may readily be prepared from wheat, 
or from flour, by the agency of cold water, and pressing 
out the starch. It has a grey colour; is elastic, ductile, 
and tenacious ; soon decomposing when kept long in con- 
tact with the air, emitting an offensive odour similar to that 
of putrid animal matter. Gluten, when burnt, affords simi- 
lar products to albumen, or white of egg, and differs little 
from it in composition. It is found in a great number of 
plants : in acorns, chestnuts, apples, rye, barley, wheat, 
peas, and beans ; in the berries of the elder, and in grapes. 
Gluten appears to be one of the most nutritive of the vege- 
table substances ; and wheat seems to owe its superiority to 
other grain, from the circumstance of containing it in larger 
quantities. Animal gelatin, its counterpart from the ani- 
mal kingdom, enters largely into the composition of many 
of the animal solids ; such as horns, hoofs, and skin, the 
organized structure of bone, cartilage, and tendon. Isin- 
glass and common joiner's-glue are forms of gelatin, it 
being readily distinguished from all animal principles by its 



38 PRODUCTIVE FARMING. 

easy solubility in boiling water. Gluten and albumen, de- 
rived from vegetables, differ from other vegetable products, 
principally in containing nitrogen, and thus assimilating 
very closely to the chemical character of animal matter. 
Its composition is 47 parts of carbon, 8 of hydrogen, 27 of 
oxygen, and 18 nitrogen, in 100 parts, or pounds. 

Woody fibre is a substance remaining after the plant 
subjected to analysis has been exhausted of all its soluble 
materials by repeated boiling in water and spirit of wine. 
It forms the bulk of vegetables. Its composition is 52 parts 
of carbon, and 48 of hydrogen and oxygen, in such pro- 
portions as form water, in 100 parts. Jinimal fibrin is a 
principal constituent of the muscular, red or fleshy parts of 
animals, and of the blood. It may conveniently be pro- 
cured by stirring blood recently abstracted, during its coag- 
ulation ; then washing the fibres till they become colourless, 
or by digesting small pieces of lean meat in repeated por- 
tions of water. As vegetable charcoal is made largely 
from woody fibre subjected to the action of a close fire, so 
animal charcoal may be similarly prepared from the mus- 
cular parts of animals by the same agency ; or, indeed, 
from any organized structure containing carbon. In ani- 
mal fibrin, as it exists in muscle or in blood, one-half the 
weight is carbon. Fibrin is white, inodorous, and insipid ; 
w^hen dry, it is hard, brittle, and slightly transparent. 
Strong sulphuric acid blackens it, converting it into char- 
coal precisely as it does wood. In the roots of plants, in 
the trunk and branches of trees, the bark and heart-wood, 
the leaves and flowers, the great basis of the solid parts is 
woody fibre. It forms by far the greatest part of the heart- 
wood and bark ; there is less in the alburnum, still less in 
the leaves and flowers. Fibrin holds a similar relation to 
animal bodies. In 100 parts of fibrin there are 53 J of car- 
bon, hydrogen 7, oxygen 19, and 19 of nitrogen i the 
presence of nitrogen, or its addition, constituting the pecu- 
liarity which distinguishes fibrin from woody fibre. 

We have run the parallel far enough for ordinary pur- 
poses. Of course, there are some proximate compounds in 



PRODUCTIVE FARMING. 39 

animals and vegetables which are not common to both, 
though, with the usual addition of another element, nitro- 
gen, the most varying and unlike substances derivable from 
the animal and vegetable world are compounded from the 
same ultimate elements. Let us next briefly glance at a 
few of these. 

Starch. — Starch is procured from different vegetables, 
but particularly from wheat, or from potatoes. To make 
starch from wheat, the grain is steeped in cold water till it 
becomes soft, and yields a milky juice by pressure ; it is 
then put into sacks of linen, and pressed in a vat filled 
w^ith water : as long as any milky juice exudes, the pre- 
sure is continued, the fluid becomes gradually clear, and a 
white powder subsides, which is starch. Arrow-root, tapio- 
ca, and sago, are nearly pure starch. Starch, or, in its ab- 
sence, coagulated mucilage, forms the greatest part of the 
seeds and grains used for food ; and they are generally 
combined with gluten, oil, or albumen : in corn with glu- 
ten, in peas and beans with albumen, and in rape-seed, 
hemp-seed, linseed, and the kernels of most nuts, with oils. 
Its characteristic property is its easy solubility in boiling- 
water, and its insolubility in that fluid when cold. The ulti- 
mate composition of starch is, carbon 43J, oxygen 60, 
hydrogen 6^ ; or, in other words, carbon 43|-, and oxygen 
and hydrogen in such proportions as form water ; differing, 
chemically, from gum, only in a very slight variation in 
these quantities. 

Extract, or the extractive principle, exists in almost all 
plants. It may be procured in a state of tolerable purity 
from saffron, by merely infusing it in water, and evapo- 
rating the solution. It may likewise be obtained from 
catechu, or terra Japojiica, a substance now imported in 
immense quantities from India, and used in calico-printing. 
This substance consists principally of astringent matter and 
extract. By the action of water upon it, the astringent 
matter is first dissolved, and may be separated from the 
extract. There are almost as many varieties of extract as 
there are species of plants. It is not, nor can it be used 



40 PRODUCTIVE FARMING. 

singly as an article of food ; but is probably nutritive 
when united to starch, mucilage, or sugar. Its con)po- 
sition is carbon, hydrogen, oxygen, and a little nitrogen. 

Tannin^ or the tanimig principle, may be procured by 
the action of cold water on bruised grape-seeds, or pound- 
ed gall-nuts, and by the evaporation of the solution to 
dryness. It is a yellow, highly-astringent substance. If 
tannin be distilled in close vessels, the principal products 
are charcoal, carbonic acid, and inflammable gases, with a 
minute quantity of volatile alkali. Hence its ultimate ele- 
ments seem the same as those of extract, but probably 
in different proportions. Tannin is not a nutritive sub- 
stance, but is of great importance in its application to 
the art of tanning. When skins (which are composed al- 
most entirely of gelatin or jelly) are exposed to solu- 
tions containing tannin, they slowly combine with that 
principle ; their fibrous texture and coherence are preserv- 
ed ; they are insoluble in water, and no longer liable to 
putrefaction ; and, by subsequent processes of rolling and 
drying, form leather. In general, in this country, the re- 
quisite tannin is made from the bark of the oak; but 
the barks of other trees, and the wood and leaves of many 
shrubs, yield it abundantly. 

Resin is very common in the vegetable kingdom. 
One of the most usual species is that afforded by the dif- 
ferent kinds of fir. When a portion of the bark is re- 
moved from a fir-tree in spring, a matter exudes, which 
is called turpentine. By heating this turpentine gently, a 
volatile oil rises from it, known familiarly as " spirit of tur- 
pentine." A more fixed substance remains, which is com- 
mon yellow rosin. Resins are insoluble in water, but very 
soluble in spirit of wine; in this respect reversing the cha- 
racter of gum. Sandarac, copal, mastic, elemi, are resins 
obtained from various trees ; and the list is very numerous. 
Tar and pitch principally consist of resin in a partially de- 
composed state. Tar is made by slowly burning the fir ; 
and pitch, by the evaporation of the more volatile parts of 
tar. One hundred parts of common resin contain 76 of 



PRODUCTIVE FARMING. 41 

carbon, 13.3-lOths of oxygen, and 10.7-lOths of hy- 
drogen. 

Wax is found in a number of vegetables, from their 
berries and the surfaces of their leaves. Its combustible 
property, like that of resins, is well known. The wax of 
the vegetable kingdom seems to be precisely of the same 
nature as that afforded by the bee. Its constituents are, 
carbon 81.7-lOths, oxygen 5^, hydrogen 12.6-lOths, in 
100 parts. 

Fixed oil is obtained by expression from seeds and fruits. 
The olive, the almond, linseed, and rape-seed, afford the 
most common vegetable fixed oils. Their common proper- 
ties are well known. They are lighter than water ; and 
many of them congeal at a lower temperature than that at 
which water freezes. They all require, for their evapora- 
tion, a higher temperature than that at which water boils. 
The products of the combustion of oil are, water and car- 
bonic acid gas. The fixed oils are very nutritive substan- 
ces : they are of great importance in their applications to 
the purposes of life. Fixed oil, in combination with soda, 
forms the finest kind of hard soap. Let us compare the 
ultimate analysis of olive or vegetable oil with that of sper- ^ 
maceti oil, which is of animal origin : — 



Olive Oil. 




Spermaceti Oil. 




Carbon, . . 


77.2-lOths 


Carbon, 


50. 


Oxygen, . 


9.4-lOths 


Oxygen, 


5. 


Hydrogen, . 


. 13.4-lOths 


Hydrogen, . . . . 


45. 



100. 



100. 



The greater proportion of hydrogen in spermaceti oil ren- 
ders it a fitter fluid for combustion in lamps than vegetable 
fixed oils ; but the ultimate composition of the two, as far 
as the list of ingredients is concerned, is evidently the same. 

Hog's lard, butter, spermaceti, may be regarded as ani- 
mal fixed oils. 

Volatile, or essential oils, differ from fixed oils, in being 
capable of evaporation by a much lower degree of heat 
Volatile oils give the peculiarity of odour to the pepper- 
mint plant, to camomile, and numberless other shrubs and 

3* 



42 PRODUCTIVE FARMLXG. 

trees; existing in the flowers of some of them, and in the 
leaves and inner bark of others. Thousands of minute in- 
sects may usually be seen in the stalk and leaves of the 
rose ; but none of them are ever observed on the flower. 
One reason for the existence of fragrant volatile oil in 
plants may be, the preservation of the parts destined to the 
propagation of the species from the destructive ravages of 
insects and animalculse which feed on the bodies of plants. 
So, those woods that contain aromatic oils are remarkable 
for their indestructibility, as cedar, rose-wood, and cypress. 
The volatile oils inflame with more facility than fixed oils; 
and afford, by their combustion, different proportions of the 
same substances — namely, water, carbonic acid, and char- 
coal or carbon. Volatile oils consist of carbon, hydrogen, 
and oxygen ; but, as yet, no accurate experiments have de- 
cided their relative proportions. 

The hitter 'principle is very extensively diffused in the 
vegetable kingdom. It is found abundantly in the hop, in 
the common broom, in camomile, and in quassia. The 
natural bitter principle is of great importance in the art of 
brewing. It checks fermentation, and preserves fermented 
liquors, and doubtlessly plays an important part in the 
healthy nutrition of the living vegetable. An intensively 
bitter substance is found in bile, or the fluid secreted 
by the liver of animals. The gastric juice, or fluid secret- 
ed by the stomach, is not only the principal solvent in di- 
gestion, but has the same antiseptic property, or resists pu- 
trefaction as strongly as the vegetable bitter principle. 

Systematic writers on chemistry have enumerated a 
long list of proximate constituents, both of animal and 
vegetable structure. Many of them, as we have seen, are 
but the counterparts of each other. It is needless to spe- 
cify them all. 

The earths found in plants are four, all of them, as 
previously related, of metallic origin. These are, l^^, Sil- 
ica, or the earth of flints, the base of which is the metal 
silicon ; 2d, Alumina, or pure clay, the base of which is 
the metal aluminium ; 3c/, Lime, the metallic base of which 



PRODUCTIVE FARMING. 43 

is calcium ; and, Atlily, Magnesia, the metallic base of 
which is magnesium. All of these are similarly found in 
animals ; among them, lime, most largely in their bones and 
shells. Some insects are almost entirely composed of sil- 
ica : iron, existing in peat-mosses and in many vegetables, 
gives the red colour to the blood. None of these exist in 
a free or uncombined state, in either the vegetable or ani- 
mal world ; most commonly in combination with acids, of 
which we may observe, that some plants contain free veg- 
etable acids in large proportion, as the common sorrel or 
sour-leaf The applications of the vegetable acids are 
well known. The agreeable taste and wholesomeness of 
various vegetable substances used as food, materially de- 
pend upon the vegetable acid they contain. Phosphoric 
acid (united to lime in bones) is found free in the onion ; 
and the sulphuric, muriatic, and nitric acids, though they 
cannot with propriety be considered as vegetable products, 
exist in many saline compounds, as part of the inorganic 
constituents of plants as well as animals. They are all 
variously compounded of carbon, hydrogen, and oxygen. 
Then, too, the saline compounds found in plants correspond 
with many similar compounds found in animals. Potash 
and soda, blended with acids, are found in blood, in the va- 
rious animal secretions, in the leaves and stalks of vegeta- 
bles; sparingly in animal matter, very largely in sea-w^eed 
yielding soda, and in the ashes of burnt wood yielding 
potash. 

Plants, like animals, are produced by ordinary genera- 
tion ; and though we meet with various instances of pro- 
duction by the generation of buds and bulbs, or of slips and 
oiFsets, the similarity, instead of being liereby diminished, 
is only drawn the closer ; for we meet with just as many 
instances of the same variety of propagation among ani- 
mals. Many species of worms are capable of increase 
by buds, bulbs, or offsets; and some of these animals, like 
the house-leek and various grasses, by spontaneous sepa- 
ration. A twig of myrtle will live and grow, if placed in 
the ground, because it contains in itself all the parts of a 



44 PRODUCTIVE FARMING. 

perfect plant ; but that is independent of the provision na- 
ture has made for the propagation of the plant naturally, 
from the seed buried in the earth. Something approach- 
ing very closely to the character of a sexual, or reproduc- 
tive system of organs, is visible in the flowers of plants. 
The pistil is the organ which contains the rudiments of the 
seed ; but the seed is never formed, as a reproductive germ, 
without the influence of the pollen, or dust on the anthers. 
This mysterious impression is necessary to the continued 
succession of the different vegetable tribes. It is a feature 
which extends the resemblances of animal and vegetable 
existence, and establishes, on a great scale, the beautiful 
analogy of nature. Seeds which are shed devoid of this 
fructifying dust, are precisely analogous to eggs over which 
the influence of the male bird has never been exerted. 
Vitality is therefore essential to the germination of seeds : 
life will remain dormant, inert for an indefinite period, — 
and then change its form into that of active vitality, if that 
seed be placed under the action of moisture, heat, and air. 
So that the scriptural inquiry, " How^ can a seed quicken, 
unless it die ?" is not to be taken as the enunciation of a 
scientific truth, but as an illustration drawn from the ordi- 
nary apprehensions of mankind. 

The utmost period of time to which seeds may be kept, 
and be enabled to retain their life, and, consequently, their 
power of growth, has not been accurately determined ; but 
we have proofs enough to show that the duration may be 
very long. A paper of melon seeds, found in the year 
1762 in a cabinet of Lord Mortimer, and apparently col- 
lected in 1660, were then sown, and produced excellent 
fruit ; and, more latterly, seeds buried in the ruins of Her- 
culaneum, and others brought from Egypt, — found in the 
tombs that are more ancient than the time of Moses, — have 
been proved to retain their vitality. Animal seeds, or, 
more properly, eggs, when perfectly impregnated, appear 
capable of preservation quite as long. This inert condi- 
tion of seeds is not unlike what occurs in the hollows of 
our waste lands, in reference to animal matter. When 



PRODUCTIVE FARMING. 



45 



these have been for some time filled with stagnant Avater, 
we not unfrequently find minute eels, minnows, and water 
insects there, and wonder how they could get into such a 
situation. But the mud which has been emptied out of a 
fish-pond has been, perhaps, thrown into these very hol- 
lows ; or the eggs of the animals or insects have been carried, 
mixed with other materials, into the same place, and then 
waiting, it may be, year after year, the accidental, yet ne- 
cessary, circumstances of warmth, water, light, and air, 
they have been stimulated to active life. One species of 
locust appears, m numbers, only once in seventeen years ; 
and the palmer-worm once only, in similar numbers, in 
thirty years. Something analogous to this occurs in refer- 
ence to various species of grub and fly, as observed by 
practical farmers ; and the reason of it is, that the integu- 
ment, or outer covering, of many minute ova, ensures their 
protection and their vitality during long periods. The eggs 
of the gad-fly could never be hatched on the horse's back : 
their covering preserves them entire and vital, till, by the 
itching sensation their presence excites, the animal is 
tempted to lick the spot, and so convey them to his stom- 
ach, the only place where it is destined they should come 
to maturity. Numberless small fish are seen in the salt 
pans at a village, in Hesse Darmstadt : the ova of these 
fish have been conveyed there by birds, and, it so happens, 
are deposited in a place, where the necessary conditions 
exist for their development. 

The essential difference between the egg of a barn-door 
fowl, and the ovum or egg, which ultimately becomes a 
calf, a foal, or a human being, is, that the one, after the 
stimulus of impregnation has been applied to it by the male, 
comes to maturity within the body of its parent ; in the 
other instance, it is hatched after its expulsion. In fish and 
in frogs, the spawn, or ova, is first expelled, then the male 
passes over it. The seeds of plants are exactly analogous to 
eggs ; in ordinary instances the germs and the fecundating 
material which ensures reproduction, being both found in the 
same flower, and, of course, attached to the same stalk. 
The various species of fruit are but contrivances for the 



46 PRODUCTIVE FARMING. 

shelter and preservation of seeds, as the pippins of the ap- 
ple, or of the orange and lemon : these, when fully ripe, 
left to themselves, would fall, become rotten, or, in other 
words, subjected to common chemical agencies and expos- 
ing the seed within, form, in the first instance, a manuring 
material for the perpetuation of the plant or tree which 
had yielded it. 

Plants derive all their sustenance from the spot on 
which they are placed ; and, solely for this reason, are not 
provided with a pecuharity which distinguishes animals, 
namely, a set of movable levers or bones, destined to 
carry them about from place to place in quest of food, and 
of muscles, or red, fleshy, contractile organs, intended to act 
upon those passive levers: and yet there are some plants 
that seem fairly entitled to the character of locomotive or 
migratory. A familiar instance of this occurs in the straw- 
herry genus : such plants grow from a new bulb, or knob, 
or radicle, while the old root dies away ; in consequence of 
which, we can only conclude that the living principle of the 
plant has quitted an old, decayed, and ruinous mansion, to 
take possession of a new one ; so much so, that were a per- 
son to plant the orchis, or the devil's-bit, in his garden, and 
to search for it in the same spot, after an interval of seven 
years, he would find it several hundred yards from the spot 
where he had planted it. 

There are some creatures that throw off their outer cov- 
reing annually : so the shrubby cinquefoil, indigenous to 
Yorkshire ; and other plants and trees, which, sending 
forth, every spring, new colonies, by means of runners, 
(as we call them,) shortly obtain a settlement for themselves, 
and break off all connexion with the parent stock. 

The blood of plants, like that of animals, is of an ex- 
tremely compound character. If blood be allowed to stand 
n a vessel, it soon separates into a clot, and a fluid in which 
that clot floats. Each of these is again divisible into seve- 
ral other matters. So with the fluid that circulatesin the 
vessels of a tree. And, as from blood the various dissimi- 
lar solid and fluid secretions and excretions are formed, 



PRODUCTIVE FARMING. 47 

building up the animal fabric, — as bone, muscle, bile, 
urine, jelly, — so, from this common current of vitality, 
the sap, plants, like animals, secrete a variety of sub- 
stances of different, and frequently of opposite pow- 
ers and qualities — substances nutritive, medicinal, or dc" 
structive. The flesh of the viper is healthful, his poison is 
deadly ; the root of the Indian cassava is poisonous, its 
leaves are eaten as ordinary food. Every one is familiar 
with the fact, that some of our domesticated animals will 
eat with impunity vegetables that would be poisonous to 
others. Then, too, how close is the analogy between the 
torpidity of the squirrel, or the dormouse, or the swallow, 
during the winter, and that of deciduous plants during 
the same season : we know, that if proper care be exer- 
cised, they may be removed in that state without endan- 
gering their vitality. Many animals are amphibious — they 
can live equally well on land or in the water; and the vege- 
table world is not without illustrations of a similar power. 
Indeed, the instances of resemblance between animal and 
vegetable life are innumerable. Some vegetables, like a 
few birds, more insects, and most of our forest beasts, ap- 
pear to sleep through the day, and become active at night; 
while the greater number of them, like the great ma- 
jority of animals, fold or hang their leaves at sunset, and 
appear invigorated with the return of morning. Like ani- 
mals, the duration of their existence is equally various. 

We have already observed, that plants and animals con- 
vert the materials of nutriment they receive into their own 
substance precisely by the same agency, and that there is 
no essential difference between the ultimate composition of 
the requisite materials in either instance. If this be so, as 
in the further progress of this inquiry we shall unquestion- 
ably prove, it would be fair to expect that the digestive 
organs of animals, — in fact, all that is connected with re- 
production and growth, — have their counterpart in plants; 
and such is actually the case. Let us briefly review the 
anatomy, or organized structure, of a plant, and compare 
that structure with the anatomy of a horse. 



48 PKOUUCTIVE FARMING. 

Every plant, examined as to external structure, displays, 
at least, four systems of organs, or some analogous part. 
First, the Root ; Secondly, the Trunk and Branches, or 
Stem ; Thirdly, the Leaves ; and. Fourthly, the Flowers 
or Seeds. 

The stem of any tree consists of the pith in the centre, 
the wood surrounding the pith, and the bark which 
covers the whole. A tree completely divested of bark, is 
precisely in the predicament of an animal deprived of its 
hide. The pith consists of bundles of minute hollow tubes, 
or vessels arranged horizontally ; the wood and inner bark, 
of long tubes or vessels bound together in a vertical posi- 
tion, so as to be capable of carrying vegetable blood up 
and down between the roots and leaves. When a piece of 
wood is sawn across, the cut ends of these tubes are as dis- 
tinctly perceptible as the divided arteries and veins in the 
stump of an amputated limb. Branches are only prolong- 
ations of the stem, and have the same character. 

The bark of the stem and root is divisible, like the cov- 
ering of animals, into epidermis, (analogous to the scarf 
skin which rises over a blister,) and tnce skin, or inner 
bark, which alone is vascular and vital. In forest trees, 
and in the larger shrubs, the bodies of which are firm, the 
outer bark, epidermis, or scarf skin, is a part of little im- 
portance ; but in reeds, grasses, and plants having hollow 
stalks, as wheat and oats, it is of great use, and is exceed- 
ingly strong, from the provision of its containing siliceous 
earth, or the oxide of a metal, as already stated. The 
analogy between this contrivance and the shell of the lob- 
' ster, or the covering of insects, is very obvious. 

As the 7^oot tapers away, the pith gradually disappears, 
the bark thins out, the wood softens, till the white tendrils, of 
which its extremities are composed, consist only of a colour- 
less, spongy mass, in which the vessels or tubes that carry 
on the circulation lose themselves. 

The leaf is an expansion of the twig. Each separate 
leaf is precisely analogous in its action to the gills of a 
fish, or the lungs of an ox, or of a human being. The 



PRODUCTIVE FARMING. • 49 

fibres \vhich are seen to branch out from the base over the 
inner surface of the leaf, are prolongations of the vessels 
of the wood, precisely as the lung of an animal is but an 
outspread division of blood vessels. A powerful sucking 
and forcing pump called the hearty is essential to drive 
human blood along large vessels to its ultimate division; 
but the vessels of plants are capillari/, that is hair-like, 
exceedingly minute, and therefore a central power or heart 
is not necessary. So there are capillary vessels in animals, 
and there the action of the heart is not so sensibly felt. 
Their minuter blood vessels are believed by some to be 
contractile. The green exterior portion of the leaf is a 
continuation of the inner bark, and communicates directly 
with its vessels. Most of the vessels of the living plant 
are full of sap or vegetable blood in almost continual mo- 
tion. In spring and autumn the motion is more rapid ; in 
winter it is sometimes scarcely perceptible. From the 
spongy part of the root the sap ascends through the vessels 
of the wood in virtue of that capillary attraction already 
adverted to, until it is diffused over the inner surface of the 
leaf. By the vessels in the green of the leaf it is returned 
to the bark, and through the vessels of the inner bark it is 
returned to the root. In man and four-footed animals the 
blood is driven from the heart along the arteries, and returns 
back by the veins; but previously to being sent along the 
circulation a second lime, it is driven into the lungs, is 
there subjected to the action of the air, (whence the neces- 
sity for breathing,) and then, returned to the other side of 
the heart, is agaki fitted to recommence its journey. Ani- 
mals derive a considerable portion of their nutriment from 
the change effected on the air by the action of the lungs : 
something is absorbed as well as given out. The leaves of 
plants perform the same oflnce. In the sunshine, the leaves 
are continually absorbing carbonic acid as well as other 
matters from the air, and giving out oxygen gas. In 
breathing, carbonic acid is given off, and not triflingly. 
The air becomes instantly poisonous, if that gas accumu- 
late as rapidly as it did when some hundreds of our brave 



50 PRODUCTIVE FARMING. 

countrymen were pent up in the confined space of the 
^' black-hole" at Calcutta. The leaves, then, are con- 
tinually appropriating carbon, the basis of charcoal, from 
the atmosphere. When night comes, this process ceases, 
and they begin to absorb oxygen and give off carbonic 
acid. Hence the mischief of placing large plants, in great 
numbers, in bedrooms. It would result from the above ar- 
rangement, that plants grow very little, perhaps not at all, 
during the night. Now, during the summer months, when 
they are provided with leaves, the days are long, the nights 
short ; in winter, when plants are torpid or stationary, the 
nights are long, and the day comparatively brief. Sun- 
shine is necessary, in order to enable plants to decompose 
carbonic acid and appropriate the carbon. It is owing to 
this law, that in the cold northern regions where, in their 
highest latitudes, the sun once risen never sets again during 
the whole of their short summer, vegetation almost rushes 
up from the soil ; almost literally, plants may be seen to 
grow. The green leaves are continually gaining from the 
air and never losing ; ever taking in and never giving off 
carbon, since no darkness interrupts or suspends their labors. 
Every child is led to regard the root of a plant as the 
organ from which the vegetable grows ; not merely as at- 
taching it in the erect position to the spot, but as forming 
the medium of communication between all that is above 
ground, and the food the soil is supposed to yield. But it 
is not so obvious to us, who, in many senses, are but child- 
ren of a larger giowth, that the leaves of an oak or an ash 
spread their broad leaves into the air for the very same pur- 
pose as the roots diffuse their fibres through the soil. The 
only difference is, that while the roots absorb chiefly liquid, 
the leaves inhale almost solely gaseous food. The human 
lungs expose the blood to air just as, in the leaf, the sap is 
submitted to the same agency ; and in each instance there 
is a double use to which these organs are destined : they 
not only change the character of the circulating fluid, but 
permit, by the decomposition of air, the absorption of some 
of its elements as food for the animal or plant. So that, 



PRODUCTIVE FARMING. 51 

in truth, we live and are nourished partly upon the air we 
breathe^ and so is a cabbage upon the atmosphere it decom- 
poses. If the experiment be repeated — it has often suc- 
succeed— that of burying the branches of certain trees in 
the soil and elevating the roots in the atmosphere, turning 
the vegetable upside down — there is as it were an inversion 
of its functions — the roots will produce buds and leaves, 
and the branches shoot out into root-like fibres and tubes. 
The experiment succeeds well with the willow. 

Though plants give out in the night carbonic acid, this 
process does not go on so rapidly, or to such an extent, as 
to destroy the balance in their favour of w^hat has been ab- 
sorbed during the day. The quantity absorbed through the 
leaves varies with the season, the climate, and the kind of 
tree ; it is also modified by the nature of the soil. It has 
been ascertained, however, that in our climate, on an 
average not less than from one-third to three-fourths of 
the entire quantity of carbon contained in the crops we 
reap from land of average fertility, or (pretty nearly) the 
amount of charcoal a burnt hay-stack would yield, is really 
obtained from the air. 

The varied and equally important uses of a leaf appear, 
to the contemplative mind, singularly beautiful. 

" In human works, though laboured on with pain, 
A thousand movements scarce one purpose gain ; 
In God's, one, single, can its ends produce, 
Yet serves to second, too, some other use." 

Then, too, the contrivance of so many expanded leaves ! 
The air contains only one gallon of carbonic acid in every 
2500; and this fortunately, rather w^e ought to say de- 
signedly, only in a state of mixture, not of combination, 
with the elements of the atmosphere, and therefore more 
easily separable; were the proportion larger, it would 
prove poisonous to the animals that live in it, deriving also 
a portion of their nourishment from another element of the 
atmosphere equally essential to plants. Now, in order to 
catch this minute quantity of carbonic acid, the tree hangs 
out thousands of square feet of leaf, in perpetual motion 



52 PRODUCTIVE FARMING. 

through the ever-moving air; and thus, by the conjoined 
labours of millions of pores, the substance of whole forests 
of solid wood is slowly extracted from the fleeting winds. 
Is not this wonderful ! Green stems, and stalks of grasses, 
absorb carbonic acid as the leaf does ; and thus a larger 
supply is afforded when the growth is most rapid, or when 
the short life of the annual plant demands much nourish- 
ment in a limited time. The slender and comparatively 
dry leaves of the pine and the cedar perform the same func- 
tions as the large and juicy leaves of the fig-tree, the cab- 
bage, the walnut, or the rhubarb plant. That plants 
derive so large a proportion of their nutriment, not from 
the soil, but from the air, is evident from observing the 
habitudes of many found in hot climates, which refuse to 
vegetate except in a soil so dusty that no moisture can be 
extracted from it, and perish if water be ignorantly supplied 
to them. A well-known Jamaica shrub was long propa- 
gated in our own stoves by cuttings, which, though freely 
watered, could never be made to produce any signs of 
flowers or fruit, notwithstanding that the cuttings were 
several feet in length every season. By accident, a pot 
with young cuttings was mislaid and forgotten in the royal 
garden, and having no water given it, it was thereby re- 
duced to its healthy dryness, and then every extremity was 
seen to produce a flower. It is an opinion common to 
many able men of the present day, that many plants derive 
the whole of their support from the surrounding atmos- 
phere ; if this be true of some, it is partially true of all, 
and must very materially modify all our plans intended to 
increase the product of the soil. There are, we say, some 
plants which have no root whatever, as in the prickly-pear 
or Indian fig; many are attached only to the hard surface 
of a stone, and propagate their kinds by offsets, without 
any other vegetable organs. Now there are some quad- 
rupeds that appear to derive nourishment in the same way. 
The sloth never drinks : it imbibes moisture by its skin, it 
trembles at the feeling of rain ; so the olive cavy, and the 
ostrich, are noted by the Arabs as avoiding water, and yet 



PRODUCTIVE FARMING. 



53 



these creatures are as juicy and well supplied with fluids 
as any with which we are acquainted. 

If leaves are necessary for the existence of the indivi- 
dual tree, the flowers are necessary as generative organs 
for the continuance of the species. Even in that class of 
plants where no flowers are distinct, still there is every rea- 
son to believe that the production of the seed is effected in 
the same way as in other plants. Mosses and lichens, which 
belong to this family, have no distinct roots, but they are 
furnished wi.h filaments which perform the same functions; 
and even in mushrooms there is a system for the absorption 
and exposure of the sap to the air. Of all parts of plants 
the flowers are most refined, the most beautiful in their 
structure, and appear as the master-work of nature in the 
vegetable kingdom. The elegance of their tints, the va- 
riety of their forms, the delicacy of their organization, and 
the adaptation of their parts, are all calculated to awaken our 
curiosity and excite our admiration. The ancients had ob- 
served, that diff'erent date-trees bore different flowers; and 
that those trees producing flowers, containing in their cen- 
tre organs termed by botanists ^' pistils,^' bore no fruit un- 
less in the immediate neighbourhood of such trees as pro- 
duced flowers differently arranged in their central structure, 
and containing " stamens " The great naturalist, Lin- 
naeus, has arranged the whole Vegetable Kingdom into 
twenty-four classes, as deducible from the numbers of these 
sexual organs in each flower. The numbers of the stamens 
and pistils in each, their arrangements or their division, are 
the circumstances which guided him, and enabled him to 
form a system of botany admirably adapted to assist the 
memory, and denoting well the analogies of all the essen- 
tial parts of plants. 

The SEED, the last production of vigorous vegetation, is 
wonderfully diversified in form. Being that part which is 
of the highest importance, it is found defended above all 
other parts of the plant ; sometimes by soft pulpy sub- 
stances, in addition to a hard shell, as in apricots and 
plums ; by thick membranes, as in common garden peas 



54 PRODUCTIVE FARMING. 

and beans ; by hard shells, or a thick coating, as in corn 
and grasses. So, similarly, the eggs of the ostrich, which 
are destined to be hatched by the sun in the sand where 
they are deposited, are invested with a strong shell, not 
firmer, comparatively, than the encasement surrounding 
every one of the myriads of ova or eggs in the roe of a 
cod-fish or herring. If w^e were to pursue the analogy 
more closely still, between the structure of a grain of w^heat 
and that of the egg of a bird or the ovum of a quadruped, 
we should find the parallelism singularly minute and exact ; 
but this is the province of the physiologist : it is enough 
for our purpose to cite a familiar illustration. When pota- 
toes are cut in pieces for seed, every gardener know^s that, 
if each separate piece have not an " eye" upon it, the frag- 
ment will not grow^ If it vegetate, it will be from that 
living spot or " eye :" the remainder wall serve to minister 
nutriment to the infant plant before it can pierce the soil ; 
it will strike upwards and downwards; the original bit of 
potato will be absorbed, or perish. So, a common garden 
bean is divisible into two equal halves or lobes, which form 
the organ of nourishment ; but the young plant springs not 
from these, but from the plume or small white point be- 
tween their upper part, and the young root is found like a 
small curved cone at the other end of the seed. In wheat, 
and many grasses, the organ of nourishment is not divisible 
as in a bean ; but the same principle holds true not only of 
all seeds, but of bird eggs, and the rudimentary ova of all 
animals. 



CHAPTER IV. 

Of the Elementary Composition of Water ; of the Composition of the 
jitmosjjhere ; and of the artificial Application of Water to Grass 
Lands. 

We have already traced some of the more prominent 
analogies obviously existing between vegetables regarded 
as alive, and animals. We have shown that the ultimate, 
and many of the proximate, elements of both are the same 
— that they are nourished or destroyed by the same agen- 
cies. Before we describe minutely the nature of the pro- 
cess of nutrition and growth, it is necessary to understand 
the chemical composition of the atmosphere, which is re- 
lated similarly to lungs as to leaves; and of water, neces- 
sary alike to plants as to animals. 

If one measure of hydrogen gas, and half as much 
oxygen gas, or, by weight, eight grains of oxygen gas, and 
one grain of hydrogen, be mixed in a dry glass over mer- 
cury, and the mixture set on fire, the result will be the for- 
mation of 'pure water. So water is formed, and is some- 
times seen collected, from the burning of the common 
carburetted hydrogen, in the street or shop gas-lamps -, the 
effect being nothing more nor less than the combination of 
the oxygen of the air with the burning hydrogen. Water 
is the result of their union, and combustion, or burning, 
EFFECTS that union. The gas in the pipes would not, could 
not, burn, if a free supply of air, or rather of oxygen, con- 
tained in that air, were cut off; and water is the product 
of their union. So that perfectly pure water is, chemically 
speaking, not a simple undecompounded element, but a 
compound of two elements — oxygen and hydrogen ; both 
of which, as elements, enter largely into the composition 
of both animal and vegetable matter. Oil and fat owe 



56 PRODUCTIVE FARMING. 

their utility in yielding light in lamps to the presence of 
hydrogen. Its presence causes turpentine and rosin to blaze 
and burn readily ; while oxygen is equally an ultimate in- 
gredient in all vegetable and animal substances. These 
details may appear scientific; but the action of manure is 
not to be understood without them, or rather the nature of 
vegetable and animal growth, and all that favours or 
retards it. 

The purest natural water we can obtain is procured 
by melting snow, or collecting rain-water, in stations dis- 
tant from the smoke of a town. If pure water be requisite 
for the experiments of a chemist, it is generally obtained 
by distilling rain-water in glass vessels, — that is, raising it 
into steam by heat, then allowing that steam to condense, 
by passing it through cold pipes. The characters of abso- 
lutely pure water are — that it is perfectly transparent and 
colourless, limpid, not sparkling, insipid, unpleasant, and 
sickly to the taste, and is lighter than common river or 
spring water. One hundred cubic inches of water weigh 
252.^ grains; it is 828 times heavier than air ; and when 
expanded into steam, occupies 1700 times its previous space. 
Steam is not nearly so heavy as the air. Water readily 
absorbs many gases : what is called soda-water, is water 
impregnated with fixed air, or carbonic acid gas. It ab- 
sorbs ammoniacal gas readily in large quantities, forming 
what is sold in the shops as spirit of hartshorn. 

Of the constitution of Sea Water, the proportions and 
nature of its saline ingredients, one of their final uses in 
vegetation, and especially the relatively large proportion 
of carbonic acid it contains, we will speak, when advert- 
ing to the necessity and wisdom of such arrangement. 

Neither is the atmosphere animals breathe and decom- 
pose, and in which living plants carry on analogous opera- 
tions, a simple element. Air is a compound of two gases, 
oxygen and nitrogen^ in the proportion of two parts of iii- 
trogeii to one of oxygen. 100 cubic inches of air weigh 
30 grains. The atmospheric pressure of the air upon the 
earth's surface, at the level of the sea, is equal to a weight 



PRODUCTIVE FARMING. 67 

of 15 pounds upon every square inch, and is capable of 
supporting a column of water 34 feet high, or of mercury, 
30 inches. For this reason, a pump will not work, if the 
depth of the shaft be greater than 34 feet; and the height 
to which the quicksilver will rise in the weather-glass al- 
ways corresponds to the pressure of the atmosphere; that 
is to say, the weight of the mercury in the tube is exactly 
equal to the weight of a column of air the same thickness, 
only the height of the atmosphere. The air receives its 
heat entirely from the earth : hence the phenomena of cold 
which we perceive the higher we ascend from the earth's 
surface. 

If water be passed through a red-hot gun-barrel, it \vill 
be decomposed ; its oxygen will unite with the metal, its 
hydrogen will escape, and may be collected in the form of 
a gas, and preserved in a bladder. Many similar experi- 
ments demonstrate the composition of water. It may be 
made, in fact is made, in almost every instance where a 
combustible body unites with the oxygen of the air : it may 
be separated into its elements, unmade, so to speak, by a 
variety of processes. Synthesis is the term chemists apply 
to the former ; analysis to the latter mode of demonstrat- 
ing its composition. 

JVbidJ, it is most materially iinporfant, in connexion with 
our future inquiries, to observe, that there are other matters, 
not essential to the composition either of air or water, 
that IN NATURE are always found mechanically mixed up or 
associated with each, and this as an express provision for 
the sustenance of animals and plants. 

The atmosphere is not compounded purely of oxygen and 
nitrogen ; it contains carbonic acid and watery vapour. The 
proportion of carbonic acid in the atmosphere may be re- 
garded as equal nearly to one part in a thousand, estimated 
by weight. The quantity varies according to the seasons, 
but the yearly average remains continually the same. 

And the rain that descends from the clouds contains am^ 
monia, one of the elements of which, as previously stated, 
is nitrogen. Experiments confirm the theory upon which 

4 



68 PRODUCTIVE FARMING. 

the presence of ammonia in rain-water might reasonably 
be expected. If a few hundred pounds of rain-water be 
carefully subjected to distillation, and the first two or three 
pounds evaporated, with the addition of a litlle muriatic 
acid, a very distinct crystallization of muriate of ammonia, 
or sal ammoinac, may be obtained, which crystals have a 
brownish-yellow colour. If a little sulphuiic or muriatic 
acid be added to a quantity of rain-water, and the mixture 
boiled to dryness, tbe ammonia remains as the residue, in 
combination with the acid employed ; and it may be detect- 
ed by the addition of a litlle powdered lime, which, com- 
bining with the acid, sets the ammonia free, and is recog- 
nised by its pungent smell. The sensation which is per- 
ceived upon moistening the hand with ra/Ti-water, so dif- 
ferent from that produced by washing it in pure distilled 
w-ater, and to which the term soft7iess is applied, is owing 
to the presence of carbonate of ammonia in rain-water. 

Hotv this ammonia is generated in rain-water, the im- 
portance and utility of the fact, and the uses of carbonic 
acid in the atmosphere, are matters so closely identified 
with living processes in animals and plants, that we must 
here simply confine ourselves to the statement. "We have 
now the preliminary materials for the examination of nu- 
tritive actions. When these, as they exist naturally, are 
understood, we shall be able to say what are those substan- 
ces called FERTILIZING, which may be useful in given instan- 
ces as manure, whether their application may be suitable 
or injurious ; just as a knowledge of anatomy and physi- 
ology is necessary to the physician who would amend the 
diseased conditions of the body. He must know what is 
the nature of healthy and ordinary action in the living 
frame, before he can understand and alter diseased action. 

The artificial application oi water in large quantity to 
the land, is a subject well understood, and its effects accu- 
rately marked and recognised in many parts of the world 
tliHt have been regarded as strictly agricultural localities 
during a long succession of ages. Irrigation is, in truth, 
a mode of applying the weakest of liquid manures, on a 



PRODUCTIVE FARMING. 69 

very bold scale, to grass-lands. Almost every farmer has 
a mode of accounting for the highly-fertilizing effects of 
rigaiion. Davy added another to the list of explanations. 
He thought that a winter-flooding protected the grass from 
the injurious effects of the frost. He examined, with a 
thermometer, and with his usual address, the water- mea- 
dows near Hungerford, in Berkshire, and ascertained that 
the temperature of the soil was ten degrees higher than the 
surface of the water, and that, too, on a frosty March morn- 
ing. He remarked, also, a fact that most farmers will 
confirm, that those waters which breed the best fish are 
ever the best fitted for watering meadows. 

He appears, however, never to have steadily investigat- 
ed the chemical composition of river-water with regard to 
its uses in irrigation ; and in consequence, he knew little of 
the value of some of its impurities to vegetation. Thus, if 
the river-water contains gypsum, (sulphate of lime,) which 
it certainly does if the water ishar'd, it must, under ordinary 
circumstances, on this account alone, be highly fertilizing 
to meadows, since the grasses contain this salt in very sen- 
sible proportions. Calculating that one part of sulphate 
of lime is contained in every two thousand parts of the 
river-water, and that every square yard of dry meadow- 
soil absorbs only eight gallons of water, then it will be 
found, that by every flooding, more than one hundred weight 
and a half of gypsum per acre is diffused through] the soil 
in the water : a quantity equal to that generally adopted 
by those who spread gypsum on their clover, lucern, and 
sainfoin crops as a manure, either in a state of powder, or 
as it exists in peat-ashes. 

And, if we apply the same calculation to the organic 
substances ever more or less contained in flood-waters, and 
if we allow only 25 parts of animal and vegetable remains 
to be present in a thousand parts of river-water, then we 
shall find, taking the same data, that every soaking with 
such water will add to the meadow nearly two tors per 
acre of animal and vegetable matters ; which, allowing in 
the case of water-meadows five floodings per annum, is 



60 PRODUCTIVE FARMING. 

equal to a yearly application of ten tons of organic matter. 
The quantity of foreign substances present in river-water, 
although commonly less, yet very often exceeds the pro- 
portion we have calculated to exist. 

There is no stream more celebrated for its prolific water- 
meadows than the Itchen in Hampshire ; and in no part 
of Eno-land is the system of irrigation better understood and 
more zealously followed. The water of this river, taken 
from above the city of Winchester, contains in 10,000 
parts, after all its mechanically suspended matters have 
subsided, about 2.2-3d parts, namely — 

Organic matter . . , . . 0.02 parts. 
Carbonate of lime (chalk) . . .1.89 

Sulphate of lime (gypsum) . . . 0.72 
Muriate of Soda (common salt) . . 0.01 

The water of lakes is usually still more surcharged with 
foreign substances than those of rivers ; and, from the use 
of such waters, especially if an occasional or winter stream 
of water passes through them, we have witnessed great 
fertilizing eff'ects produced on meadow land. 



CHAPTER V. 



Of the Nature of Vegetable Growth; thejtrue use of Vegetable 
Mould or Humus ; and of the Sources of the Elementary Con- 
stituents of Plants. 

• From the facts detailed in the foregoing sections, the 
development or nutrition and growth of a plant requires 
the presence, first, of substances yielding carbon and nitro- 
gen, as elements to the growing structure ; secondly, ot 
water, furnishing in itself two very important elements, 
namely oxyen and hydrogen, besides adventitious matters ; 
and lastly, a soil, to yield the saline, earthy, metallic, or 
other organic materials essential to vegetable life. 



RODUCTIVE FARMING. 61 

The fertility of every soil is generally supposed to de- 
pend on the presence in it of a peculiar substance, named 
"Awmw.9." This substance, incorrectly supposed to form 
the principal nutriment of plants, and to be extracted from 
them by the soil in which they grow, is nothing more than 
vegetable mouldy the product of the decay of other plants. 

Adherence to the above incorrect opinion, has hith- 
erto rendered it impossible for the true theory of the nutri- 
tive process in vegetables to become known, and has thus 
deprived us of our best guide to a rational practice in agri- 
culture. Any great improvement in that most important 
of all arts, is inconceivable without a deeper and more per- 
fect acquaintance with the substances which really nourish 
plants, and with the sources whence they are derived. It 
was supposed that by the aid of water " humus" is rendered 
capable of being absorbed by the roots of plants. If it be, 
it must be in some altered Ibrm ; for if a portion of good 
mould be long subjected to the action of water, that fluid 
will not dissolve more than a hundred-thousandth part of 
its weight, and contain only soluble organic matters, and 
the salts which are contained in the rain-water which has 
fallen upon it. Decayed oak wood, beech, and fir, yield 
the same results. 

Let us inquire whence the grass in a meadow, or the 
wood in a forest, receives the carbon essential to the forma- 
tion of that wooPY FIBRE Constituting the principal weight 
and solid bulk of the tree or plant. Whole tracts of open 
country in the green wilds of America, immense woods and 
forests in all parts of the world, receive no carbon in the 
form of manure ; how does it happen that the soil, instead 
of being exhausted through the annual production of vege- 
tation for ages, becomes every year richer in carbon ? In 
other words, a certain quantity of carbon is taken every 
year from an unmanured forest or meadow, in the form of 
growing wood or grasses ; and in spite of this, the quantity 
of carbon in the soil augments; it becomes richer in vege- 
table mould, in humus — so much so, that in process of time 
it will not support the trees which stood upon it : they fall, 



69 PRODUCTIVE FARMING. 

and the surface becomes a peat-moss, burying huge trunks 
in its bosom. Plants give back more carbon to the soil 
than they take from it ; it is evident, then, that their growth 
must depend on the reception of carbon as food from another 
quarter. It is not denied that manure, rightly chosen 
and applied, exerts an influence upon the growth of plants; 
but it neither serves for the | roduclion of the carbonaceous 
woody fibre, nor has any influence upon it, because we find 
that the quantity of carbon produced by manured land is 
not greater than that yielded by lands which are not ma- 
nured. The discussion as to what manure really produces, 
has nothing to do with the present question, which is, the 
origin of the carbon as the principal element of the woody 
fibre. It must be derived from other sources ; and as the 
soil does not yield it, we are driven to look for it in the at- 
mosphere. 

Now% we have already stated that the air contains car- 
bonic acid ; and if the reason of its presence there be not, 
that it may yield carbon to plants, what other use can be 
assigned to it ? Animals do not derive their chief suste- 
nance from the air : to them pure and unmixed carbonic 
acid is poisonous ; though taken into the stomach it is 
grateful. Besides, we know it to be a fact, that during 
the sunshine of day the leaves of plants are continually ab- 
sorbing this very gas, and giving out oxygen; and if not 
for their nutrition and growth, for what other purpose? 
Carbonic acid being a compound of carbon and oxygen, 
they retain the carbon and give out the oxygen. This has 
been long known ; but it is only a recent discovery, that 
the sole source of woody fibre is the atmosphere. 

Mould, or humus, can only arise from the decay of 
plants. No primitive mould can have existed ; for plants 
must have preceded the mould, which this theory assumes 
as necessary to their existence. Whence, then, did the 
first vegetables derive their carbon, if not, as now, from the 
surrounding air ? We shall arrive at satisfactory conclu- 
sions respecting the mode in which animal, as w^ll as 
vegetable, life and nutrition are maintained, by observing 



PRODUCTIVE FARMING. 63 

how the uninterrupted uniformity of proportion is secured 
in the quantities of the elements composing the atmosphere. 
How does it happen that, with such an immense expendi- 
ture of oxygen as occurs in the combustion of countless 
millions of tons of coal, and in the consumption of that gas 
in the lungs of the myriads of creatures that live on the 
earth's surface, still the composition of the atmosphere is 
invariably the same ? 

The answer to this question depends upon another. 
What becomes of the carbonic acid which is produced by 
the breathing of animals, and in every instrmce where a 
combustible body is burnt ? There is no change of volume ; 
for the oxygen extracted from the atmosphere by a coal 
fire is replaced by ihe same bulk of carbonic acid, and sim- 
ilarly in every breath w^e draw. The immense masses of 
carbonic acid which flow into the atmosphere from so many 
causes ought perceptibly, after 6000 years, to increase its 
quantity. 

A cause must exist which prevents the increase of car- 
bonic acid, by removing that which is continually forming; 
and there must be some means of replacing the oxygen 
which is removed from the air by combustion, breathing, 
and putrefaction. 

Both these causes are united and displayed in the 'pro- 
cess of vegetable as well as of animal life. The facts we 
have already stated prove that the woody fibre, or carbon 
of plants, must be derived exclusively from the atmosphere. 
Now, carbon exists in the air only in the form of carbonic 
acid, and, therefore, in a state of combination with oxygen. 

Besides, as already stated, carbon and the elements of 
water form the principal constituents of vegetables. Now, 
the proportion of oxygen in the whole mass of a plant is 
less than in carbonic acid. It is, therefore, certain that 
plants must possess the power of decomposing carbonic 
acid, since they appropriate the carbon for their own use. 
The formation of woody fibre, gum, starch, and the various 
substances containing carbon — that taken together com- 
pose a plant — must necessarily be attended wuth the sepa' 
ration of the carbon of the carbonic acid in the air from 



64 PRODUCTIVE FARMING. 

the oxygen of that acid. This oxygen is returned to the 
atmosphere, as experiment and observation prove, though 
its source is only just understood. And the carbon enters 
into composition with water, or its elements in the plant. 
The atmosphere must thus receive a volume of oxygen for 
every volume of carbonic acid which has been abstracted 
from it and decomposed. The leaves and green parts of a 
plant emit an equal quantity of oxygen in exchange for the 
carbonic acid they absorb, and they will do this even when 
torn from the stem on which they were just growing. 
Each acre of land which produces eight hundred weight 
of carbon, (say woody fibre,) gives annually to the atmos- 
phere about two thousand six hundred pounds of free oxy- 
gen gas ; so that an acre of meadow, wood, or cultivated 
land, replaces, therefore, in the atmosphere as much oxy- 
gen as is exhausted by eight hundred weight of carbon, 
either in its ordinary destruction by burning, or in the ac- 
tion of the lungs of animals. 

Plants not only separate all noxious matters from the 
air, — they form, by this arrangement, an inexhaustible 
source of pure oxygen to supply that loss the air is con- 
stantly sustaining. Animals, on the other hand, throw off 
carbon from their lungs, which plants take in by their 
leaves ; and thus the composition, or the relative propor- 
tions of the elements forming that medium in which they 
both exist, is maintained constantly unchanged. 

Many conditions are necessary for the life and growth 
of plants. Each kind requires special conditions; and 
should but one of these be wanting, although all the rest 
be supplied, the plants will not be brought to maturity. 
It is in vegetable as in animal life : a mother crams her 
child exclusively with arrow-root; it becomes fat, it is 
true ; but alas ! it is rickety, and gets its teeth very slow- 
ly and with difficulty. Mamma is ignorant, or never thinks 
that her offspring cannot make bone, or, what is the same 
thing, phosphate of lime, the principal bulk of bone, out 
of starch. It does its best ; and were it not for a little 
milk and bread, perhaps now and then a little meat and 
soup, it would have no bones and no teeth at all Farmers 



PRODUt:TlVE FARMING. 65 

keep foultry ; and what is true of fowls, is true of a cab- 
bage, a turnip, or an ear of wheat. If we mix with the 
food of fowls a sufficient quantity of egg-shells, or chalk, 
which they eat greedily, they will lay many more eggs 
than before. A well-fed fowl is disposed to lay a vast 
number of eggs; but cannot do so without the materials 
for the shells, however nourishing in other respects her 
food may be. A fowl, with the best will in the world, not 
finding any lime in the soil, nor mortar from walls, nor 
calcareous matter in her food, is incapacitated from laying 
any eggs at all. Let farmers lay such facts as these, which 
are matter of common observation, to heart, and transfer 
the analogy, as they justly may do, to the habits of plants, 
which are as truly alive, and answer as closely to evil or 
judicious treatment as their own horses. The organs of 
plants, like those of animals, contain substances of the 
most different kinds. Some are formed solely of carbon 
and the elements of water : as, for instance, woody fibre, 
resin, gum, and starch; some contain nitrogen : as, for in- 
stance, the gluten of wheat ; and in all plants we find me- 
tals in a state of combination with oxygen. The food 
which can serve for the production or increase of any, or of 
all the organs of a plant, must necessarily contain the ele- 
ments of that part, or set of parts. Dogs die although fed 
with jelly, which contains nitrogen in abundance : they 
cannot live upon white bread, sugar, or starch, if these 
are given as food, to the exclusion of other substances. 
Can it be concluded from this, that these things contain no 
elements suited for nutrition 1 Certainly not. 

Because a vegetable is alive, it has the power of con- 
stantly reproducing itself; for this it requires a supply of 
substances which contain the constituent elements of its 
own substance, and which are susceptible of undergoing 
the necessary transformation. All the organs together, 
whether of animal or vegetable life, have not the power to 
generate, that is, to produce out of nothing a single ele- 
ment. A dog would die in the vacuum of an air-pump, 
even though supplied with a superabundance of food ; it 

4* 



66 PRODUCTIVE FARMING. 

will die in the air if no food be given to it ; it will die in 
oxygen gas, however freely it may be supplied with nour- 
ishment. But it is not hence to be concluded, that neither 
flesh, nor air, nor oxygen, is fitted to support life. They 
are all admirably calculated to do so; so it is just as rea- 
sonable to expect to bring a plant to perfection, — wheat, 
for instance, — which, in its healthy and natural state, con- 
tains silica, or potash, if it be planted in a soil destitute of 
such inorganic materials, or to which they have not been 
added. When we are acquainted with the nature of 
a single cubic inch of that soil, and know the composition 
of air and rain-water, we are in possession of all the con- 
ditions necessary to their life. The source of the different 
elements entering into the composition of plants, cannot 
possibly escape us, if we know in what form they take 
up their nourishment, and compare its composition with 
that of the vegetable substances which compose their 
structure. 

Vegetables undergo, after death, two processes of decom- 
position : one of these is for mentation, the other is putre- 
faction. Decaying leaves, stalks, or roots, are, in fact, 
undergoing a slow process, analogous to combustion ; inas- 
much as it is the combination of the combustible parts of a 
plant, (structures that will burn,) with the oxygen of the 
atmosphere. 

The decay of woody fibre (the principal constituent 
of all plants) is accompanied by appearances of a peculiar 
kind. This substance, in contact with air or oxygen gas, 
and no longer preserved from chemical decomposition by 
the living principle which has now left it, unites with that 
gas, and the product is an equal volume of carbonic acid. 
The property which woody fibre in a state of decay has to 
form carbonic acid with the surrounding oxygen of the 
atmosphere, diminishes as the decay advances, till it is com- 
plete, and ceases. Mould constitutes the principal part of 
brown coal and peat. An atmosphere of carbonic acid, 
formed at the expense of the oxygen of the air, surrounds 
every particle of decaying vegetable matter ; hence the 



PRODUCTIVE FARMINO. ^ 

value of ploughing, digging, and otherwise loosening the 
soil : it permits the access of air. An atmosphere of car- 
bonic acid is therefore contained in every fertile soil, and is 
the first and most important food for the young plants before 
they reach the surface. The leaves of trees which fall ia 
the forest in autumn, and old roots of grass in a meadow, 
are converted into what is termed humus by the same 
a2;ency ; but humus does not nourish plants directly, by 
be ng taken up in its unaltered state, but by presenting a 
slow and lasting source of carbonic acid, which is absorbed 
by the roots of plants, and forms their principal nutriment 
at a time when, being destitute of leaves, they cannot, as 
yet, extract food from the atmosphere : hence one reason 
of the value of ploughing, digging, and otherwise lightening^ 
the soil, by permitting the access of air, and consequently, 
of carbonic acid to the seeds and roots. Seeds should 
always be sown, so as to be fully exposed to the influence 
of the air ; and one cause of the unproductiveness of cold, 
clayey, adhesive soils is, that the seed is coated with matter 
which the air cannot get at. In sandy soils, the earth is 
mostly sufficiently penetrable by the atmosphere ; but in 
clayey soils, there can scarcely be too great a mechanical 
tearing up and division, in the process of tillage. Many 
ploughmen know the fact, without knowing the reason of 
it : however, any seed not fully supplied with air, always 
produces a weak and diseased plant. In this way, ihen, 
we see the true uses of the vegetable decaying mould, whea 
well torn up by the plough. The roots perform the after- 
functions of the leaves : they extract from the soil the car- 
bonic acid generated from the humus, or vegetable mould j 
they decompose that acid, and absorb the carbon. Whea 
a plant is quite matured, and when the organs by which it 
obtains food from the air are fully formed, the carbonic acid 
of the soil is no longer required. 

If turnips be sown in a soil capable of yielding as much 
nourishment as they will take up, they Avill attain a much 
larger size than under the reverse circumstances. The 
size of a plant is always proportioned to the sukface of the 



68 PRODUCTIVE FARMING. 

organs which are destined to convey food to it. A plant 
gains another mouth and stomach with every new fibre of 
root, and every new leaf. 

Let us suppose a plant fully grown. All the necessary 
amount of woody fibre has been formed by the leaves. 
But the action of the leaf does not cease. Carbon is 
still absorbed ; the expenditure of nutriment, the supply 
of which continues the same, takes a new direction. The 
leaves now produce sugar, starch, gum, or acids, which 
were previously formed by the roots when these substances 
were necessary for the development of the stem, buds, 
leaves, and branches of the rising plant. The direction of 
the nutriment again changes, and blossoms are produced. 
The functions of most plants cease upon the ripening of 
their fruit, because the products of their action are no 
longer needed. They now yield to the chemical influence 
of the oxygen of the air : their feeble vitality weakly op- 
poses the decomposition which awaits all dead matter ; 
they change colour, fall off, and become converted into the 
mould of which we have been speaking. 

A cubic inch of sulphuretted hydrogen gas introduced 
intp the human lungs would cause instant death ; but it is 
often formed, under a variety of circumstances, in the 
bowels without injurious effects. Each organ, whether of 
an animal or a vegetable, extracts from the food presented 
to it what it requires for its own action and sustenance ; 
while the remaining absorbed matters, which are not nutri- 
tive, combine together, and are separated as excrement. 
The excrementitious matters of one organ come in contact 
with another during their passage through the plant or 
animal, and, in consequence, suffer 7iew transformations : 
the useless matters rejected by one organ contain the ele- 
ments for the nourishment of another, till what is utterly 
useless is expelled from the system, by contrivances for 
that purpose. So the kidneys, liver, and lungs, are organs 
of excretion : the first separate from the body substances 
in which a large proportion of nitrogen is contained ; the 
second those with an excess of carbon ; and the third, such 



PRODUCTIVE FARMING. 69 

as are composed, principally, of more oxygen and hydrogen 
than is wanted. All superabundant nitrogen is thrown 
out from the body as a liquid excrement through the uri- 
nary passages ; all solid substances, incapable of further 
useful transformation, pass out by the intestinal canal ; and 
all gaseous matters by the lungs. 

The presence of life prevents common chemical decom- 
position or putrefaction : the power to effect the trans- 
formations essential to nutrition and growth does not be- 
long to it. Each such transformation is owing to a dis- 
turbance in the attraction of the elements of a given com- 
pound, and is, consequently, a purely chemical process. 
Similar changes of existing compounds are in constant pro- 
gress during the whole life of a plant ; in consequence of 
which there are produced gaseous matters, thrown off by 
the leaves and blossoms, sohd excrements deposited in the 
bark, and fluid soluble substances which are excreted by 
the roots. Through the expulsion of these matters unfitted 
for nutrition, the soil receives back again the greatest part 
of the carbon, which it had at first yielded to the young 
plants as food in the shape of carbonic acid, from the de- 
caying mould. 

Having disposed of the question as to the origin of 
carbon in plants, and examined the relation between vege- 
table mould and the springing vegetable, we must next 
trace the source of the hydrogen and nitrogen they contain. 

All the hydrogen necessary for the formation of a plant 
or animal is supplied by the decomposition of water. From 
their generating wax, fats, and volatile oils, containing 
hydrogen in large quantity, and no oxygen, we may be 
certain that plants possess the property of decomposing 
water ; because from no other body with which they are 
placed in contact, could they obtain the hydrogen which 
exists as an element in those matters. The process ofvege- 
table growth, in its simplest form, consists in the extraction 
of hydrogen from water, and carbon from carbonic acid. 
The green resinous principle of the leaf diminishes in 
quantity while oxygen is absorbed. We can explain, in a 



70 PRODUCTIVE FARMING. 

similar manner, the formation of all the component sub- 
stances of plants which contain no nitrogen. During the 
progress of growth, plants appropriate carbon from the car- 
bonic acid found in the air, and hydrogen from the decom- 
position of water ; the oxygen of which fluid is set at liberty, 
together with a part, or all of that contained in the carbonic 
acid. Decay, then, or vegetable putrefaction, is that great 
operation of Nature by w^hich that oxyen which was con- 
sumed by plants during life is again returned to the atmos- 
phere ; for water is essential to such putrefaction. 

As to the origin of nitrogen in plants, we may observe, 
that it exists in every part of the vegetable structure. No 
plant would attain maturity, even in the richest vegetable 
mould, unless nitrogen were supplied to it. How, it may 
be asked then, and in what form, does Nature furnish nitro- 
gen to assist in the formation of vegetable albumen and 
gluten, to fruits and seeds ? 

This question is susceptible of a very simple solution. 
Plants, as we know% grow perfectly well in pure charcoal, 
if supplied at the same time — not with river or spring, or 
perfectly pure water, but with ram-water. Now% rain- 
w-ater can contain nitrogen only in two forms — either as 
dissolved atmospheric air, (which, of course, contains nitro- 
gen,) or as AMMONIA, of w'hich nitrogen is one element. 
We have observed, in speaking of the composition of water, 
that ram-water is found to contain ammonia ; and this is 
the practical application of the fact. Pure air may, for 
our present purpose, be considered as oxygen and nitrogen 
in certain unalterable proportions, in a state of mixture ; 
the carbonic acid and ammonia which float in the atmos- 
phere may be regarded as accidental ingredients. If we 
were to suppose that plants derived their nitrogen directly 
from the atmosphere, — that is, by depriving the air of a 
portion of that nitrogen which is essential to its constitution 
— we are met by many difficulties. Rain-water does not 
yield nitrogen from pure air, which it may hold in solution 
or suspension, but from ammonia, which, rising from putre- 
fied animal remains, becomes readily dissolved in the first 



PRODUCTIVE FARMING. 71 

mass of watery vapour that may present itself. We have 
no reason to believe that the nitrogen of the air takes part 
in the processes of nutrition in plants and animals ; on the 
contrary, we know that many veg«^tables emit, or give off 
the nitrogen which is absorbed by their roots. But, on the 
other hand, there are numerous facts, showing that the 
formation in plants of substances containing nitrogen, as 
gluten, for instance, in corn, takes place in proportion to the 
quantity of this element, which is conveyed to their roots 
in the state of soluble salts of ammonia, derived from the 
putrefaction of animal matter. 

All animal bodies, during their decay, yield the nitrogen, 
which they abundantly contain, to the atmosphere in the 
form of ammonia. A generation of a thousand millions of 
human beings is renewed every thirty years : countless 
millions of animals have, during that period, ceased to live. 
Where, but floating in the atmosphere, is the nitrogen 
their bodies contained during life ? Without the occurrence 
ofi^utridity and the g;eneration of ammonia, and its diffusion 
in the air, the wheels of nature would soon stop — vegetable 
and animal life could go on no longer. Ammonia is the 
simplest of all the compounds of nitrogen : the reader will 
remember our previous statement, that hydrogen and nitro- 
gen combine to form ammonia. Hydrogen is that element 
for which nitrogen possesses the most powerful affinity. 

The nitrogen, then, of putrefied animals is contain- 
ed in the atmosphere (combined with hydrogen) as 
ammonia, in the form of a gas which is capable of enter- 
ing into combination with carbonic acid, and of forming a 
volatile salt very soluble in water. Ammonia, therefore, 
cannot remain long in the air, as every shower of rain must 
dissolve it and convey it to the earth's surface, to be ab- 
sorbed and decomposed by the roots of plants. We ought 
to expect, and such is the fact, that ram-water must at all 
times contain ammonia, though not always in equal quan* 
tity. If a pint of rain-water contain only a quarter of a 
grain of ammonia, then a field of forty thousand square 
feet must receive yearly upwards of eighty pounds of am- 



72 PRODUCTIVE FARMING. 

monia, or sixty-five pounds of nitrogen; for it is ascertained 
that the annual fall of rain-v^rater over this extent of surface 
is at least 2,500,000 pounds. This is much more nitrogen 
than is contained in the form of vegetable albumen and 
gluten in 2650 pounds of wood, 2800 pounds of hay, or 
200 cwt. of beet-root, which would be the yearly produce 
of such a field ; but it is less than the strawy roots, and grain 
of corn which might grow on the same surface would con- 
tain. Animal manure, as we shall presently show, acts 
only by the formation of ammonia. Its employment in the 
cultivation of grain, and of fodder for cattle, furnishes con- 
vincing proof that the nitrogen of vegetables is derived 
from ammonia. The quantity of gluten in wheat, rye, and 
barley, is very different; and they contain nitrogen in vary- 
ing proportions. Even in samples of the same seed the 
quantity varies ; and why ? Evidently because one variety 
has been better fed with its own appropriate fertilizer, than 
another which has been reared on a soil less accurately 
adapted by artificial means for its growth. French wheat 
contains 12 per cent, of gluten ; Bavarian 24 per cent. 
Sir H. Davy obtained 19 per cent, from winter, and 24 
from summer wheat; from Sicilian 21, from Barbary 
wheat 19 per cent. Such great differences must be 

OWING TO SOME CAUSE, AND THIS WE FIND IN THE DIFFER- 
ENT METHODS OF CULTIVATION. An increase of animal 
manure gives rise not only to an increase in the number 
of seeds, but also to a remarkable difference in the pro- 
portion of gluten which those seeds contain. Among 
manures of animal origin there is great diversity. Cow 
dung contains but a small proportion of nitrogen. One 
hundred parts of wheat, grown on a soil to which this 
material was applied, afforded only 11 parts of gluten, and 
64 of starch ; while the same quantity of wheat, grown on 
a soil fertilized with human urine, yielded 35 per cent, of 
gluten, and of course a smaller proportion of less valuable 
ingredients. During the putrefaction of urine, ammoniac- 
al salts are formed in large quantity, it may be said, exclu- 
sively ; for under the influence of warmth and moisture, 



PRODUCTIVE FARMING. 73 

urea, the most prominent ingredient of urine, is converted 
into carbonate of ammonia. Putrid urine is employed in 
Flanders as a manure with the best results. The barren 
soil on the coast of Peru is rendered fertile by means of a 
manure called Guano, which is collected from several 
islands in the South Sea. It forms a layer several feet in 
thickness upon the surface of these islands, and consists of 
the putrid excrements of innumerable sea-fowl that remain 
on them during the breeding season. This substance has 
recently been imported in large quantities into England ; 
and its fertilizing powers are very extraordinary. Its price, 
about <£18 per ton, is a serious objection; and since the 
nitrogen it contains forms its principal recommendation, 
doubtlessly other matters nearer home will not be wasted, 
or their value unknown and disregarded, as to a great ex- 
tent they have been. As to the practical results of the 
application of Guano, an intelligent agriculturist in the 
neighbourhood of Hamburg has forwarded the annexed 
remarks to the Editor of the Gardener^s Chrcnide. He 
observes that " Most of the experiments with guano in the 
vicinity of this city have been made on meadows and 
lawns. On these it has produced the best possible effects ; 
so that, for instance, at Flottbeck, the patches manured 
with guano presented not only a finer and darker green, 
but the grass was closer and more rich ; so that, comparing 
it with patches not guanized, the produce of the former 
may, without exaggeration, be stated to be double. To 
give an idea of the extraordinary forcing qualities of gua- 
no, we may mention that at Flottbeck, on a spot of grass 
managed after the English fashion, the second cutting of 
the grass was necessarily five days after the first, while the 
grass growing close by, (which had not been guanized,) 
although healthy and vigorous, required double the time to 
arrive at the same state of progress. It deserves to be 
stated as something remarkable, that on the guanized spot, 
the dew^ appeared in the morning much stronger on the 
tops of the leaves, than on the part unguanized. In an 
experiment made by M. Staudinger on a barren hill, com- 



74 PRODUCTIVE FARMING. 

pnsed of granite or quartz, the guanized spot exhibited a 
dark bluish green sward, while round about nothing but 
barrenness was to be seen. If, therefore, a land owner 
wisht'Sto cover bleak hungry pasture in a short time with 
nutritious grass for cattle or sheep, the guano certainly is 
the thing to do it. It would not only produce a plentiful 
fodiler in the autumn, where cattle can be well nourished and 
prepared for the winter, but such guanized pasture will bring 
a heavy crop early in the spring. Guano has also been 
used advantageously on a sour meadow overgrown with 
horsetails; and it produced, instead of reeds and bullrushes, 
a dense turf of sweet grass, and the horsetail almost dis- 
appeared. Thus, in the first place, more grass is ob- 
tained, which may be put down as double the former 
crops ; and then the grass is very much improved in quality. 
Of course good drainage must be attended to on each mea- 
dow, if the result is expected to be complete. In using 
guano we must be careful to pulverize it well ; because, on 
account of its tenacity, it will form into lumps, and on 
places where it lies too thick, it will burn the grass, although, 
subsequently, even on such places a luxuriant herbage will 
spring up. Experiments with guano on spring crops have 
been as successful at Flottbeck, with both wheat and rye, 
as on the above meadow. The wheat manured in the 
spring with guano is much superior to that manured in the 
ordinary way, both in grain and straw. The following 
experiment was tried on a spot of almost blowing sand : — 
* On the iSth March, several square rods in the above lo- 
cality, planted with winter rye, were strewed with guano. 
The spot thus manured was in a short time not only con- 
spicuous for its dark green colour, but the tiller became so 
luxuriant as to cover the whole surface. Notwithstanding 
a drought of two months, the guanized crops remained in 
the same flourishing condition ; whilst the other rye standing 
close by had a weak and sickly appearance. Subsequently 
the former attained the height of five or six feet, with ears 
five inches long, with strong plump grain ; whilst the latter 
were scarcely half that height in straw, and their ears were 



PRODUCTIVE FARMING. 75 

barren and empty.' This experiment speaks in favour of 
guano in preference toother manure in another respect. If a 
light sandy soil like the above is manured too much wilh 
common dung, and if there follows a luxuriant vegetation, 
•with dark green foilage, we may be sure that, if there be 
subsequently any long drought, or sudden change of temper- 
ature from great heat to intense cold, rust will follow as a 
matter of course; whilst, in the above experiment, not- 
withstanding a nine-weeks' drought, and some intervening 
night frosts, the growth of the guanized rye was uniformly 
good up to the ripening of grain — a sufficient proof that 
the guano must possess the property of attracting and re- 
tainmg the fine vapour contained in the air. Hence the 
fact is to be explained why dew was more apparent on the 
guanized turf than on that not subjected to that process. 
As we know that, in general, during long drought, the ac- 
tion of dung — in fact of every manure — ceases; and as it 
is light sandy soil which first suffers from drought, it must 
be eviilent what valuable manure guano is, not only on 
pastures, but for winter rye, our chief crop on light land. 
If an acre of land is dressed with 125 lbs. of guano, an 
abundant crop of grain and straw will fully repay the ex- 
penses incurred. If such a rye-field is laid down in spring 
with meadow catstail grass {Plileum pratense) and while 
clover, a heavy grass crop in the autumn would still increase 
the advantages already mentioned. As rape can by no 
means be too luxuriant, guano would produce an extraor- 
dinary result on it." 

If a soil consist only of sand and clay, and be deficient 
of organic matter or the decaying remnants of animal or 
vegetable life, it is sufficient, and chemically correct, to add 
to it guano, in order to ensure a plentiful crop. Guano con- 
sists of ammonia in separate combination with uric, })hos- 
phoric, oxalic, and carbonic acids, together with a few earthy 
salts and some impurities. If guano be the fertilizer em- 
ployed, it is valuable, chiefly from the ammonia it contains, 
anil ammonia is valuable because one of its elements is 
nitrogen, which is yielded to the plants. Ammonia assists 



76 PRODUCTIVE FARMING. 

not only in the formation of gluten in wheat, but also in 
the production of vegetable albumen, one of the principal 
constituents of plants, and it is ammonia which forms the 
red and blue colouring of flowers. Nitrates, that is, earthy 
or metallic substances, combined with nitric acid, (which 
nitric acid is itself a comj)ound of nitrogen and oxygen,) 
are necessary constituents of several plants which thrive 
only when ammonia is present, — hence the value of nitrate 
of soda. The influence of the dried rays of the sun is to 
effect the disengagement of oxygen from the stem and 
leaves of plants, (as previously stated,) which oxygen, 
seizing upon the nitrogen contained in ammoniacal mat- 
ters, forms nitric acid, found in union with certain bases in 
many vegetables. In this way ammonia, by its transform- 
ation, furnishes nitric acid to the tobacco plant, that is, if 
it be found growing in a soil completely free from nitre or 
saltpetre, which is not nitrate of soda, but, in chemical lan- 
guage, nitrate of potass. The urine of men and of ani- 
mals living upon flesh contains a large quantity of nitro- 
gen, partly in the form of phosphates, partly as tirea, a 
substance naturally peculiar to urine. Urea is transformed 
by the putrefactive process into carbonate of ammonia ; 
that is to say, it takes the form of the identical salt which 
is always present in rain-water. Human urine is the most 
'powerful manure for all vegetables which contain nitrogen ; 
that of horses and horned cattle contains less of this ele- 
ment^ hut infnitely more than the solid excrements of these 
animals. 

In the face of such facts as these, is it not pitiable to 
observe how the urine of the stable or cowshed is of en 
permitted to run off", to sink uselessly into the earth, or to 
form a pool in the middle of a farm-yard, from which, as 
it putrefies, the ammonia formed in it is rapidly and com- 
pletely escaping into the atmosphere, to be of as great 
utility in that volatile form to a neighbour's acres as to those 
nearer home ? 

It should be the care of the farmer so to employ all the 
substances containing nitrogen which his farm affords in 



PRODUCTIVE FARMING. 77 

the shape of animal excrements, that they shall serve as 
nutriment to his own fields. This will not be the case 
unless they are properly preserved and distributed over the 
soil. A heap of manure lying unemployed would serve 
him no more than other people, if the nitrogen it contains 
be allowed to form ammonia, by combining with hydrogen. 
All animal matters emit carbonic acid and ammonia aslong 
as any nitrogen remains in them. The residue is a nearly 
worthless carbonaceous mass. All animal excrements 
emit carbonic acid and ammonia as long as nitrogen exists 
in them. In every stage of their putrefaction an escape of 
ammonia from them may be induced by moistening them 
with pearl-ashes dissolved in water, the ammonia being 
apparent to the senses by its pungent effect on the nostrils. 
This ammonia evolved from manure is imbibed by the soil 
either in solution in water, or in the form of gas ; and thus it 
is that plants may artificially be made to receive a larger 
supply of nitrogen than is naturally afforded to them by 
the surrounding atmosphere. Cultivated plants receive, of 
course, the same quantity of nitrogen from the air as trees, 
shrubs, and wild plants ; but this, of course, is not enough 
for the purposes of agriculture ; cabbages, wheat, potatoes, 
and apples being very different things in their wild, or, more 
properly, their natural state. The object of forest culture 
is, the production of carbon or woody fibre ; of garden or 
field culture, chiefly the addition of as much nitrogen as 
the plant can be made to take up. 

The solid excrements of animals do not contain as much 
nitrogen as those which are voided in a liquid form ; and, 
for this reason, do not constitute so powerful a fertilizing 
material. This could not be otherwise. The quantity of 
food which animals take, diminishes or increases in pro- 
portion as it contains more or less of the substances con- 
taining nitrogen. The bowels of the cow are relatively 
much longer than those of the tiger ; the bulk of food 
consumed by the former animal is greater, and it requires 
to be retained longer, to traverse a greater extent of 
surface, before it can yield all its nutriment, than occurs in 



78 PRODUCTIVE FARMING. 

animals feeding on flesh, which contains so much nitrogen. 
A horse may be kept alive upon potatoes, which contain 
very little nitroc^en ; but life thus supported is gradual 
starvation. So the quantity of rice which an inhabitant of 
the East Indies will eat astonishes an Englishman ; but 
the fact that rice contains less nitrogen than any other 
kind of grain, at once explains the circumstance. In hot 
countries human beings live sparingly on vegetables which 
contain little of this principle ; in very cold countries, 
human beings require very fat substances, in order to sup- 
port existence, and to enable them to generate as much 
animal heat as is necessary. The Esquimaux will devour 
amazing quantities of whale's blubber, and would speedily 
die (in that climate) without a free supply of food con- 
taining large quantities of nitrogen. Hence, vegetation is 
scanty — for food it is scarcely necessary : they live upon fish, 
or animals caught in the chase. In tropical climates, on 
the contrary, where animal food is not so necessary, a 
luxuriant vegetation is provided to satisfy the natural 
wants of man. 

By means of manure an addition only is made to the 
nourishment supplied from the air ; for the excrements of 
all animals contain less nitrogen than their food, and conse- 
quently a smaller quantity of matter containing nitrogen is 
given to the soil than has been abstracted in the form of 
grass, hay, or seeds. 

Another reason why liquid excrements containing am- 
monia (or that which, by further spontaneous chemical 
action yields ammonia, and consequently nitrogen) are 
more useful than solid excrements, is to be found in the 
fact, that the former contain the greatest part of their am- 
monia in the state of salts : in a form, therefore, in which 
it has lost its volatility when presented in this condition, 
not the smallest quantity of ammonia, in such a shape, is 
lost to the 'plants, — it is all dissolved by water and imbibed 
by their roots. Practical farmers see the results : they 
know that plaster of Paris or gypsum, the insoluble sul- 
phate of lime, strikingly increases the luxuriance of meadow 



PRODUCTIVE FARMING. 79 

grass upon which it is strewed. But why ? Because it 
fixes in the soil all the ammonia of the atmosphere, which 
would otherwise be 'partially volatilized with the water 
that constantly evaporates from the surface of the soil. 
The sulphuric acid of the sulphate of lime has a stronger 
affinity for ammonia than it has for lime ; so sulphate of 
ammonia is formed, which is not volatile, does not escape 
into a neighbour's pastures. In such an instance, the 
carbonate of ammonia naturally contained in rain-water is 
decomposed by the gypsum, in precisely the same manner 
as occurs in the manufacture of sal-ammoniac. Soluble 
(but not volatile) sulphate of ammonia, and carbonate of 
lime or chalk, are formed by double decomposition ; so 
that the beneficial eflfects of gypsum as a manure are not 
direct, but indirect, hy fixing the ammonia either of rain- 
water or of manure with which it may have been mixed, 
and thus presenting that ammonia, or its valuable element 
nitrogen, to the roots of plants in a form susceptible of 
absorption. All the gypsum gradually disappeais, but its 
action upon the carbonate of ammonia continues as long as 
a trace of it exists. 

It is quite evident, therefore, that science alone can 
truly explain the mode in which certain matters exert their 
beneficial agency ; and consequently science alone can ra- 
tionally direct the practical farmer. All else beside is 
mere experiment,— hazardous, expensive, and conjectural. 

In order to form an idea of the effect of gypsum, it may 
be sufficient to remark, that ICO pounds of burnt gypsum 
fixes as much ammonia in the soil as 6250 pounds of horses' 
urine would yield to it. The decomposition of gypsum 
does not take place instantaneously ; it proceeds very grad- 
ually, and this explains why the action of gypsum lasts for 
several years ; the supply of ammonia from the air, of course, 
remaining steady and unfailing. 

All rust of iron (or iron in combination with oxygen) 
contains a certain quantity of ammonia : the advantage of 
manuring fields with burned clay depends upon the presence 
of oxide of iron. Now, all minerals containing alumina, 



80 



PRODUCTIVE FARMING. 



or oxide of iron, possess, in a remarkable degree, the pro- 
perty of attracting ammonia from the atmosphere, and of 
retaining it in the soil. Pipe-clay, (which is aluminous 
earth,) when moistened with a solution of caustic potash, 
emits ammonia, which it has absorbed from the atmosphere 
Soils, therefore, containing oxides of iron, and burnt clay, 
must absorb ammonia, which is separated by every shower 
of rain, and conveyed, in a dissolved state, to the roots of 
vegetables. Charcoal possesses a similar action ; it will 
absorb ninety times its volume of ammoniacal gas, which 
may again be separated simply by moistening it with water, 
in which ammonia is extremely soluble. This explains 
why plants will grow in pure charcoal moistened with 
RAiN-water. We have here another easy and satisfactory 
method of explaining still further the properties of humus, 
or of wood in a decaying state. Decayed oak-w^ood ab- 
sorbs 72 times its w^eight of ammonia ; humus, then, is not 
only a slow and constant source of carbonic acid, (repair- 
ing the loss of that which is constantly decomposed and 
absorbed by the leaves of vegetables, as before stated,) but 
it is a means by which the necessary nitrogen is mechani- 
cally conveyed to plants. 

No conclusion can have a better foundation than this, 
that it is the ammonia of the atmosphere which furnishes 
all the nitrogen to plants they receive while uncultivated. 
All the innumerable products of vitality resume, after death, 
the original form from which they sprung ; and thus death, 
the complete dissolution of an existing generation of ani- 
mals and plants, becomes the source of life for a new one, 
and of that artificial 7ir\A forced amount of nutriment which 
plants may be compelled to receive, if judiciously fed, or, 
in other words, manured. 




CHAPTER VI. 

Of the Sources of the Saline, Earthy, and other Unorganized 
Constituents of Vegetables. 

A further question arises : Are the conditions already 
considered all that is necessary for the life and growth of 
plants ? It will now be shown that they are not. 

Carbonic acid, water, and ammonia, are necessary for 
the existence of vegetation, because they contain the e/c- 
ments from which their organs are formed ; but other sub- 
stances are requisite (as silica in straw) for the formation 
of certain organs destined for special functions peculiar to 
each family of plants. Plants obtain these substances from 
inorganic nature. In the ashes of burnt vegetables the same 
substances are found, although in an altered condition. — 
Many of these inorganic constituents vary according to the. 
soil in which the plants grow ; but without a certain num- 
ber of them, according to the nature of such plant, they 
never arrive at maturity. All substances that water will 
dissolve in a soil are absorbed by the roots of plants ex- 
actly as a sponge imbibes a liquid indiscriminately. The 
substances thus conveyed to plants, are either retained in 
greater or less quantity, or are entirely separated when not 
suited for nutritive purposes. 

Phosphate of magnesia^ in combination with ammonia, 
is an invariable constituent of the seeds of all kinds of 
grasses. It is contained in the outer husk, and is intro- 
duced into bread, along with the flour, as part of the bran. 
When ammonia is mixed with beer, this salt is precipi- 
tated. 

Most plants contain acids of very different composition 
and properties, all of which are in combination with bases, 
such as potash, soda, lime, or magnesia. These bases evi- 
dently regulate the formation of the acids; for example, the 

5 



82 PRODUCTIVE FARMING. 

quantity of potash contained in the juice of the grape is 
less when it is ripe than when unripe ; and the acids, 
under the same circumstances, are found to vary in a simi- 
lar manner. We glanced, in a former section, at the exid- 
ence of inorganic acids and bases in vegetables : we have 
now to investigate their source. 

The acids found in the different families of plants are 
very various. It cannot be supposed their presence and pe- 
culiarities are the result of chance or accident. They must 
serve some end in vegetable life, independently of their 
utility to the animals for whose healthful use some, if not 
all, of them are ultimately destined. Acids constantly ex- 
ist in vegetables ; and it is incontestable that ihey are ne- 
cessary to their life. And it is equally certain that some 
alkaline, earthy, or metallic base, is also indispensable, in 
order to enter into combination with such acids which are 
always found in the state of salts, as oxalate of potash in 
the sour-leaf or sorrel. 

The nature of a soil exercises a decided influence on the 
quantity of the different metallic oxides contained in the 
plants which grow on it. It is not known in what form 
silica, manganese, and oxide of iron, are contained in 
vegetables ; but we know that potash, soda, and magnesia, 
can be extracted from all parts of their structure, in 
the form of salts of organic acids. As these acids and 
bases are never absent from plants, and as even the 
form in which they present themselves is subject to no de- 
viation, it may be affirmed that they are necessary, as exer- 
cising an important influence over the development of 
fruits and seeds, and also on many other functions, of the 
nature of which we are at present ignorant. The perfect 
development of a plant is dependent, then, on the presence 
of alkalies, or alkaline earths ; when these substances are 
totally wanting, its growth will be stopped ; when they 
are only deficient, it must be correspondingly impeded. 
Firs and pines find a sufficient quantity of alkalies in bar- 
ren, sandy soil ; and wheat thrives in another kind of soil : 
because the bases necessary to bring each to maturity exist 



PRODUCTIVE FARMING. 83 

there in sufficient quantity. The proportion of silicate of 
potash (necessary for the firmness of wheat straw) does not 
vary perceptibly in the soil of corn-fields, because what is 
removed by the reaper, is again replaced in putrefying 
straw. But this is not the case with meadow-land. Hence 
we never find a luxuriant crop of grass on sandy and lime- 
stone soils which contain little potash, evidently because 
one of the constituents indispensable to the growth of the 
plants is wanting. If a meadow be well manured, we re- 
move, with the increased crop of grass, a greater quantity 
of potash than can, by a repetition of the same manure, be 
restored to it. So, grass-land manured with gypsum soon 
ceases to feel its agency. But if the meadow be strewed 
from time to time with wood ashes, or soap-boilers' ley 
made from wood ashes, then the grass thrives as luxuriantly 
as before. And why ? The ashes are only a means of re- 
storing the necessary potash for the grass stalks. So oats, 
barley, and rye, may be made for once to grow upon a 
sandy heath, by mixing with the scanty soil the ashes of 
the heath-plants that grow upon it. Those ashes contain 
soda and potash, conveyed to the growing furze or gorse 
by rain-water. The soil of one district consists of sand- 
stone ; certain trees find in it a quantity of alkaline earths 
sufficient for their own sustenance. When felled, and 
burnt, and sprinkled upon the soil, oats will grow and 
thrive that without such aid would not vegetate. 

The most decisive proof of the absurdity of the indis- 
criminate use of any strong manure was obtained at Bin- 
gen, a town on the Rhine, where the produce and develop- 
ment of vines were highly increased by manuring them 
with animal matters, such as shavings of horn. After 
some years, the formation of the wood and leaves decreased 
perceptibly. Such manure had too much hastened the 
growth of the vines : in two or three years they had ex- 
hausted the potash in the formation of their fruit leaves and 
wood; so that none remained for the future crops, as shav- 
ings of horn contain no potash. Cow-dung would have 
been better, and is known to be better. A knowledtre of 



84 PRODUCTIVE FARMING. 

chemistry furnishes the reason, which is found in the fac, 
that it contains a large proportion of potash, though very 
little nitrogen. Hence, if nitrogen be the element in 
demand, cow-dung is not the material that will yield it. 
All the potash contained in the food consumed by a cow, 
is again immediately discharged in its excrements. 

A landed proprietor, in order to obtain more potash for 
his soil, planted it with wormwood, the ashes of which are 
well known to contain a large quantity of that alkali. The 
consequence was, that he rendered his land quite incapable 
of bearing grain for many years. He had entirely deprived 
the soil of its potash. Had he sown wheat upon it instead 
of wormwood, he w^ould have found the soil contained as 
much potash as was necessary for the nutrition of that 
vegetable. The supposition that alkalies, metallic oxides, 
or inorganic matter in general, are produced by plants, is 
refuted by such facts as these : they are absorbed by plants, 
not generated. 

Those grasses, the seeds of which furnish food for man, 
follow him like the domestic animals. Saline plants re- 
quire common salt, and seek the sea-shore. The plants 
which grow on dung-hills need ammonia and the nitrates, 
and are attracted whither these can be found, just as the 
dung-fly is to animal excrements. So, likewise, none of our 
corn plants can bear plump seeds, yielding good and plen- 
tiful flour, without a large supply of phosphate of magnesia 
and ammonia, substances which they require for their ma- 
turity. No soil is richer in them than those where men 
and animals dwell together. Where the urine and excre- 
ments of these are found, corn plants appear ; because their 
seeds cannot attain maturity unless supplied with the con- 
stituents of these matters. 

During the boiling or evaporation of saltpetre ley, the 
salt volatilizes with the wafer, causing a loss which other- 
wise could not be explained. In sea storms, leaves, in the 
direction of the wind, are covered with crystals of salt, 
twenty or thirty miles from the sea. The great storm which 
occurred in England a few winters ago, verifies this state- 



PRODUCTIVE FARMING. 85 

ment. But it does not require a storm to cause the vola- 
tilization of the salt : every breeze must carry it away. 
The sea-air is always sufficient to make a solution of ni- 
trate of silver turbid and milky. Now, as millions of tons 
of sea-water annually evaporate into the atmosphere, a 
corresponding quantity of the saline matters dissolved in it, 
common salt, muriate of potash, muriate of magnesia, and 
other matters, will be conveyed by the wind to the land. 
This volatilization is a source of considerable loss in salt- 
works where the quantity of salt in the liquor is not large. 

According to Marcel, sea-water contains in every 1000 
parts 26 of common salt, 4 of sulphate of soda, or glauber 
salt, 1^ of muriate of potash, 5J muriate of magnesia, and 
l^ of sulphate of lime or gypsum. If it be asked, whether 
there be any peculiarities in the mode of existence of sea- 
plants and fish, we know that ammonia is found in sea- 
water ; and that, while air contains only from four to six 
ten-thousandth parts of its volume of carbonic acid, sea^ 
water contains 100 times more, or 620 parts in every ten 
thousand ; so that the same conditions which sustain living 
beings on the land, are combined in the ocean, in which a 
separate world of other plants and animals exists. 

By the continual evaporation of the sea, its salts are 
spread over the whole surface of the earth, subsequently to 
be carried down by the rain, and furnishing to vegetables, 
through the micdium of the soil, those saline matters essen- 
tial to their existence. The salts of potash, magnesia, and 
soda, are not peculiar to the ocean : they are found natu- 
rally existing on the land as in the water ; but the above 
explanation accounts for the origin of alkalies in the ashes 
of plants in those cases where the soil could not have 
yielded them. Nor must we overlook the fact, that what- 
ever be the nature of the soil, or however impoverished by 
successive crops of alkaline vegetables, upon that surface 
the distant ocean is for ever, unchangingly, and silently, 
pouring the saline treasures of the great deep. Were the 
proportions of land and ocean reversed as to their extent, 
it is easy to predict the effect upon vegetation ; as it is, the 



86 PRODUCTIVE FARMING. 

existing quantity of saline material in the ocean (which 
coultl not be increased without detriment to its inhabitants) 
is amply sufficient for the more than single purpose that 
wise arrangement was destined to answer. The atmos- 
phere contains only a thousandth part of its w^eight of 
carbonic acid ; and yet, small as this proportion appears, 
it is quite sufficient to supply the whole of the present gen- 
eration of living beings with carbon for a thousand years, 
even if it were not renewed. Navigators have sailed for 
hundreds of miles along the unbroken edge of a coral reef: 
the clustering islands of the Pacific are many of them exclu- 
sively of coraline origin. Sea-water contains one twelve- 
thousandth part of its w^eight of lime ; and yet, from this 
apparently minute quantity, insect agency has raised those 
very reefs upon which many a huge ship has been dashed 
into shapeless fragments. 



CHAPTER VII. 

Of the necessary Relation between the Composition of a Soil and 
the Vegetables it is fitted to raise. Fallowing and Green Crops 
considered as Vegetable manure. 

The methods employed in the cultivation of land are 
different in every country; and when we inquire the cause 
of these differences, we are told that they "depend upon 
circumstances." Now, as few people have endeavoured to 
ascertain these circumstances, to reason correctly, and act 
from rational principle, no answer could show ignorance 
more plainly. So, when we inquire how manure acts, we 
are either met with a reply that is figurative and incorrect, 
or, with the admission that the result is all that is known 
or cared about. We are told that the excrements of man 
and animals, or, that certain mineral matters are supposed 



PRODUCTIVE FARMING. 87 

to contain an incomprehensible something, which assists 
in the nourishment of plants, and increases their size. No 
attempt is made to ascertain the component parts of the 
different species of manure, much less to ascertam whether 
it be precisely fitted to supply a known deficiency in the 
soil. 

Besides heat, light, moisture, and the component ele- 
ments of the atmosphere, which are necessary for the 
mere existence of all plants, certain fertilizing substances 
are seen to exercise a peculiar influence over the develop- 
ment either of whole plants, or of particular parts of 
them. Such substances are either already contained in 
soil, or may be artificially supplied in the form of manure. 

The rules of a rational system of agriculture should 
enable us, therefore, to give to each plant that which it 
requires for the attainment of the special object in view 
— namely, an artificial increase of certain parts which 
are employed as food for man and animals. 

The means employed for the production of fine pliable 
straw for hats and bonnets is the very opposite to the mode 
which must be adopted, in order to produce the largest 
possible quantity of corn from the same plant. Peculiar 
methods must be used for the production of nitroo-en 
in the seeds; others for giving strength to the straw; 
and others again, when we wish to give such qualities 
to the straw as will enable it to bear the weight of the 
ears. 

We must proceed in the artificial rearing and forcing of 
plants precisely as we do in the fattening of animals. The 
flesh of wild animals is devoid of fat, or nearly so. The 
production of flesh and fat may be artificially increased : all 
domesticated animals are easily fattened. To do this, we 
add to the quantity of food, and lessen (as in the stall-fed 
ox) the w^aste occasioned by the increased action of the 
lungs, (as consequent upon motion,) tooether with the 
waste w-hich such muscular exertion would produce by in- 
creased action of the skin. 



88 PRODUCTIVE FARMING. 

Arable land is originally formed by the crumbling of 
rocks, and its properties depend on the nature of its com- 
ponent parts. 

Sand, clay^ and lime, are the names given to the princi- 
pal constituents of the different kinds of soil. 

Pure sand, and pure limestone, in which there are no 
other unorganized substances except the earth of flint, 
chalk, or silicic acid combined with lime, form absolutely 
barren soils. But clay always forms a part of fertile soils. 
"Whence is the origin of clay earths in arable land ? What 
are their constituents ? and what part do they play in fa- 
vouring vegetation ? They are produced by the breaking 
down of aluminums minerals by the action of the weather. 
These minerals are found, mixed with other substances, in 
granite, mica-slate, porphyry, clay slate, the volcanic rocks, 
and others. Mountain limestone is remarkable for the 
quantity of clayey earths which it contains. In grauwacke 
we find pure quartz, clay slate, and lime; in the sand- 
stones, quartz and loam; and in the transition limestone 
there is an intermixture of clay, felspar, and clay slate. 
These examples may be sufficient. 

It is known that aluminous minerals (that is to say, 
minerals containing the metal " aluminium,'^ which, com- 
bined with oxygen, forms " alumina,'^ or the pure earth 
of clay) are the most widely diffused on the surface of the 
earth; and aW fertile soils, or soils capable of culture, in- 
vaiiably contain alumina. 

There must, therefore, be something in aluminous earth 
which causes it to exercise an influence on the life of plants, 
and to assist in their growth. The property on which this 
depends is, that day invariably contains potash and soda. 
Besides which alumina attracts and retains water and am- 
monia from the atmosphere. Alumina is itself very rarely 
found in the ashes of plants ; but silica (or the earth of 
flints) is always present, having in most places, enteied 
the plants by means of alkalies. Among aluminous mine- 
rals, felspar, which is one of them, contains 17 per cent, of 



PRODUCTIVE FARMING. 89 

potash ; mica from 3 to 5 per cent, of soda : clay slate con- 
tains from 2 to 3 per cent, of potash ; and loam from 1^ to 
4 per cent, of the same alkali. 

So that, in a layer of soil formed by the breaking down 
of 40,000 square feet of one of these rocks, to the depth of 
20 inches, we should find that so much felspar would con- 
tain more than a million pounds of potash ; if the soil were 
formed by the disintegration of clay slate, about 200,000; 
if loam were the material, from 87,000 to 300,000 ; and 
similarly of other rocks of partially aluminous character. 

Potash is present in all clays, and in marl ; it has been 
found in all aluminous earths in which it has been sought. 
Alum (which is a sulphate of alumina, combined with 
sulphate of potash) may be procured by digesting clay in 
sulphuric acid, which takes up both the alumina and the 
potash. 

A thousandth part of loam mixed with the quartz in red 
sandstone, or with the lime in the different limestone for- 
mations, affords as much potash to a soil twenty inches in 
depth as is sufficient to supply a forest of pines growing 
upon it wuth potash for a hundred years. 

Water, impregnated with the carbonic acid of the at- 
mosphere, decomposes rocks which contain alkalies, and 
then dissolves a part of the alkaline carbonates formed in 
the process. Plants also, by producing carbonic acid 
during their decay, and by means of the acids emitted by 
their living roots, contribute no less powerfully to destroy 
the coherence of solid minerals. Air, water, and changing 
temperature prepare the different species of rocks for yield- 
ing to plants the potash or soda they contain. Mrs. Ellis 
relates, that among the mountains which divide France I'rom 
Spain, the rocks actually smoke after rain, under the influ- 
ence of the summer sun, and become so hot that it is un- 
comfortable to sit down upon them. Changing temperature 
is a most important agent in nature- It not only assists in 
the original formation of soils, but exerts a most powerful 
influence over those already in existence. In wet soils the 

6* 



90 PRODUCTIVE FARMING. 

temperature rises slowly, and never attains the same height 
as in one that is sandy and dry. When the heat of the 
atmosphere rises no higher in the shade than 60 or 70 de- 
grees, a dry soil may become so warm as to raise the 
thermometer to 90 or 100. Hence, though the expression 
be used figuratively, it is in this instance strictly correct to 
say that loet soils are cold. 

The exhaustion of alkalies in a soil by successive crops 
is the true reason why practical farmers sicpjwse themselves 
compelled to suffer land to lie fallow. It is the greatest possi- 
ble mistake to think that the temporary diminution of fertility 
in a field is chiefly owing to the loss of the decaying vegetable 
matter it previously contained : it is principally the conse- 
quence of the exhaustion of potash and soda, which are 
restored by the slow process of the more complete disin- 
tegration of the materials of the soil. It is evident that 
the careful tilling of fallow land must accelerate and in- 
crease this further breaking up of its mineral ingredients. 
Nor is this repose of the soil always necessary. A field, 
which has become unfitted for a certain kind of produce, 
may not, on that account, be unsuitable for another; and 
upon this observation a system of agriculture has been 
gradually formed, the principal object of which is to obtain 
the greatest possible produce in a succession of years, with 
the least outlay for manure. Because plants require for 
their growth different constituents of soil, changing the 
crop from year to year will maintain the fertility of that 
soil (provided it be done with judgment) quite as well as 
leaving it at rest or fallow. In this we but imitate nature. 
The oak, after thriving for long generations on a particular 
spot, gradually sickens; its entire race dies out; other 
trees and shrubs succeed it, till, at length, the surface be- 
comes so charged with an excess of dead vegetable mat- 
ter, that the forest becomes a peat moss, or a surface upon 
which no large tree will grow. Generally long before this 
can occur, the operation of natural causes has gradually 
removed from the soil substances essential to the growth of 
oak, leaving others favourable and necessary to the growth 



PRODUCTIVE FARMING. 91 

of beech or pine. So, in practical farming, one crop in 
artificial rotation with others, extracts from the soil a cer- 
tain quantity of necessary inorganic matters; a second 
carries off, in preference, those which the former had left, 
and neither could nor would take up. 

Experience proves that wheat should not be attempted 
to be raised after wheat on the same soil ; for, like tobacco, 
it exhausts the soil. But, if " humus," decaying vegetable 
matter, gives it the power of producing corn, how happens 
it that, in soils formed in large proportion of mouldered 
wood, the corn-stalk attains no strength, and droops per- 
manently ? The cause is this; the strength of the stalk is 
due to siliciate of potash^ and the corn requires 'phosphate 
of magnesia ; neither of which substances a soil of decay- 
inor vegetable matter can afford, since it does not contain 
them: the plant may, indeed, under such circumstances, 
become an herb, but it will bear no seeds. We say phos- 
phate of magnesia is necessary ; — the small quantities of 
the phosphates found in peas and beans is the cause of their 
comparatively small value as articles of nourishment, since 
they surpass all other vegetable food in the quantity of 
nitrogen they contain. But as the component parts of 
bone, namely phosphate of lime and magnesia, are absent in 
beans and peas, they satisfy appetite without increasing 
the strength. 

Again, how does it happen that wheat does not flourish 
on a sandy soil, and that a limestone soil is also unsuitable, 
unless mixed with a considerable quantity of clay 1 Evi- 
dently because these soils do not contain potash and soda, 
(always found in clay ;) the growth of wheat being ar- 
rested by this circumstance, even should all other requisite 
substances be presented in abundance. It is because they 
are mutually prejudicial by appropriating the alkalies of 
the soil, that wormwood will not thrive where wheat has 
grown, nor wheat where wormwood has been. 

One hundred parts of wheat straw yield 15^ of^ashes; 
the same quantity of barley straw, S} ; of oat straw, only 
4 ^ the ashes of the three are, chemically, of the same 



92 PRODUCTIVE FARMING. 

composition. Upon the same field which will yield only 
one harvest of wheat, two successive crops of barley may 
be raised, and three of oats. We have, in these facts, a 
clear proof of what is abstracted from the soil, and, con- 
sequently, what plants require for their growth, — a key to 
the rational mode of supplying the deficiency. 

Potash is not the only substance requisite for the exist- 
ence of most plants; indeed it may be replaced, in some 
cases, by soda, magnesia, or lime ; but other substances 
are required also. 

Plants obtain ;?/i05p^oWc acid (found in combination with 
lime or magnesia) from the soil, and they, in their turn, 
yield it to animals, to assist in the formation of their bones. 
Creatures that feed upon flesh, bread, fruit, and husks of 
grain, take in much more phosphorus than is required for 
rhe building up of the animal fabric ; and this excess is 
again usefully thrown out by them, chiefly in their liquid 
excrements. Some plants, however, extract other matters 
from the soil besides silica, potash, and phosphoric acid, 
which are essential constituents of the plants ordinarily 
cultivated. 

English farming presents us with varied instances of 
pl'.ints sown, and growing together in the same field. Two 
such vegetables will mutually injure each other, if they 
withdraw the same food from the soil. Plants w'ill thrive 
beside each other, either when the substances necessary for 
their growth, extracted from the soil, are of different kinds, 
or when they themselves are not both in the same stage of 
growth at the same time. On a soil containing potash, 
wheat and tobacco may be reared in succession, because 
the latter plant does not require the phosphates which the 
wheat has appropriated to itself. Now, tobacco requires 
only alkalies, and food containing nitrogen. When we 
grow different plants in the same soil, for several years in 
succession, the first of which leaves behind that which the 
second, and the second that which the third may require, 
the soil will be a fruitful one for all the three kinds of 
produce. If the first plant, for example, be wheat, which 



PRODUCTIVE FARMING. 93 

consumes the greatest part of the silicate of potash in the 
soil, the plants which succeed it should be such as require 
little potash, as turnips or potatoes. The wheat lands rnay 
be sown again with wheat, advantageously, after the fourth 
year. The reason of this is, that during the interval of 
three years, the soil will, hy the action of the atmosphere, 
be rendered capable of again yielding silicate of potash in 
sufficient quantity for wheat. Whether this process can be 
artificially anticipated, by supplying the exhausted ingre- 
dient to the soil, is a further, and most interesting inquiry. 
In a four-years' course of cropping, the crops gathered 
amounted, per acre, to — 

1st year, Turnips, 25 tons of bulbs, and 7 tons of tops. 
2d year, Barley, 38 bushels, and a ton of straw. 
3d year, Clover and Rye Grass, 1 ton of each in hay. 
4th year. Wheat, 25 bushels, and 2 tons of straw. 

Supposing none of the crops to be eaten upon the land, 
the quantity of inorganic matter contained in the above 
would be as follows : — 



lbs. 


lbs. 




Potash, 281 


Silica, 318 




Soda, 130 


Sulphuric acid. 111 j 


) in combination 


Lime, 242 


Phosphoric acid, 61 ; 


> with the earths 


Magnesia, 42 


Chlorine, 39 ] 


) and alkalies ', 



Alumina, 11 

making a gross weight of 1240 pounds, or about eleven 
hundred weight. 

A still clearer idea of the importance and quantities of 
these inorganic matters, may be obtained by a consideration 
of the fact, that if we were to carry off the entire of the 
above produce, and return none of it again in the shape of 
manure, (supposing also that we could stop the beneficial 
agency of the atmosphere during that period,) we must, or 
ought, instead of that produce, — if the land is to be restored 
to its original condition, — add to each acre, every four 
years, 300 pounds of pearl ashes, or potash ; 440 of car- 



94 PRODUCTIVE FARMING. 

bonate of soda; 65 of common salt; 240 of quick lime ; 
250 of sulphate of magnesia, that is, Epsom salts ; 84 of 
alum ; and 260 of bone dust : making 1729 pounds of solid 
saline matter, at an expense of nearly «£9. The fertility of 
a soil cannot remain long unimpaired, unless we replace 
in it all those substances of which it has been deprived. 
We could keep our fields in a constant state of fertility, by 
replacing, every year, as much as we remove from them in 
the form of produce ; and, be it remembered, that our cul- 
tivated corn plants, and bulbous roots, are not like forest 
plants and trees : the quantity of nutriment they require, 
and take up, to bring them to perfection and perpetuate the 
race, is far more than the unaided elements around them 
could supply. Wheat, for instance, as a natural production 
of the soil, appears to have been a very small grass : and 
the case is still more remaikable with the apple and the 
plum. The common crab seems to have been the parent 
of all our apples. Potatoes and turnips, in their wild or 
natural state, are unfit for food ; and two fruits can scarcely 
be conceived more different in colour, size, and appearance, 
than the wild plum and the rich magnum bonum. We 
have to contend, then, with two important differences : 
First, That wheat or turnips are not natural productions ; 
and, secondly, That because they are not, they drain or 
exhaust unassisted soil faster than the wild plants of the 
forest ; nor will they thrive long, if denied that assistance 
from artificial nutriment, which nature cannot supply in 
sufficient quantity. 

It is evident, then, that an increase of fertility, and con- 
sequent increase of crop, can only be expected when we 
add more to the soil of the proper, imterh], [and no other,) 
than we take away. Any soil will partially regain itself 
by lying fallow : this is owing to atmospheric action, and 
the conversion of the roots and stalks into humus. But 
though the quantity of decaying vegetable humus in a soil 
may be increased to a certain degree by cultivation and 
alternate cropping, still there cannot be the smallest doubt. 



PRODUCTIVE FARMING. 95 

that a soil must (without help) ultimately lose those of its 
constituents, which are removed in the seeds, roots, and 
leaves of the plants raised upon it. 

To prevent this loss, and, as a further object, to enable 
us to raise increased quantities of productions, demanding 
more sustenance than the land will naturally yield, is the 
object of the application of the various substances used as 
MANURES. They will prove useless, injurious, or valuable, 
precisely as they are accurately or inaccurately adapted to 
meet the deficiency. 

Land, when not employed in raising food for animals 
or man, should, at least, be applied to the purpose of raising 
manure for itself; and this, to a certain extent, may be 
eifecled by means o^ green crops, which, by their decom- 
position, not only add to the amount of vegetable mould 
contained in the soil, but supply the alkalies that would be 
found in their ashes. That the soil should become richer 
by this burial of a crop, than it was before the seed of that 
crop was sow^n, will be understood by recollecting that 
three-fourths of the whole organic matter we bury has been 
derived from the air: that by this process of ploughing in, 
the vegetable matter is more equally diffused through the 
w^iole soil, and therefore more easily and rapidly decom- 
posed ; and that by its gradual decomposition, ammonia 
and nitric acid are certainly generated, though not so 
largely as when animal matters are employed. He who 
neglects the green sods, and crops of weeds that flourish by 
his hedgerows and ditches, overlooks an important natural 
means of wealth. Left to themselves, they ripen their 
seeds, exhausting the soil, and sowing them annually in his 
fields: collected in compost heaps, they add materially to 
his yearly crops of corn. We have said that absolute re- 
pose of the soil is not frequently needed ; and, with some 
practical illustrations of the system of alternate cropping, 
we will close this section. 

In Flanders, two crops of clover are cut, and the third 
is ploughed in. In Sussex, turnip seed has been sown at 



96 PRODUCTIVE FARMING. 

the end of harvest, and, after two months, again ploughed 
in with great benefit to the land. So turnip leaves and 
potato tops decay rapidly, and are more enriching when 
buried in the green state. In the Earl of Leicester's 
course of cropping, the land is never idle. The turnip is 
the first in the oider of succession. This crop is ma- 
nured with recent dung, which immediately affords suffi- 
cient matter for its nourishment ; the heat produced in its 
decomposition assisting in the extrication of ammonia, the 
liberation of nitrogen, and the consequent germination of 
the seed, and growth of the plant. Next after turnips, 
barley, with grass seeds, is sown ; and the land having 
been little exhausted by the previous crop of turnips, affords 
the soluble parts of the decomposing tops and manure to 
the barley. The barley is gathered ; the grasses, rye-grass 
and clover, remain, which derive a small part only of their 
organized matter from the soil, and probably consume the 
gypsum- which would be useless to previous and succeeding 
crops. These grasses, by their large system of leaves, ab- 
sorb mainly their nutriment from the atmosphere ; and, 
when PLOUGHED IN at the end of two years, their decompos- 
ed roots and leaves are useful to the wheat crop, which is 
next, and last in succession. At this period of the course, 
the woody fibre of the farm-yard manure, containing phos- 
phate of lime, is sufficiently decomposed ; and as soon as 
the most exhausting crop is taken off the land, recent ani- 
mal manure is again applied. Pease and beans, in all in- 
stances, seem well adapted to prepare the ground for 
wheat ; and in some parts of the country they are raised, 
alternately with wheat, for years together. Mr. Gregg, — 
whose ingenious system of cultivation has been published 
by the Board of Agriculture, and who adopts, upon strong 
clays, a plan similar to that of the Earl of Leicester, (bet- 
ter known as Mr. Coke of Holkham,) — suffers the ground, 
after barley, to remain at rest for two years in grass ; sows 
pease and beans[onJthe leys; ploughs in the pea or bean stub- 
ble for wheat ; and, in some instances, follows his wheat 



PRODUCTIVE FARMING. 97 

crops by a course of winter tares and winter barley, 
which is eaten off in the spring before the land is sown lor 
turnips. 

It is a great advantRge, in the convertible system of 
cultivation, that the whole of the manure is employed as 
well as the entire resources of the land, in their proper 
order ; those materials which are not fitted for one crop, 
remaining as nutriment, or essential requisites for the next, 
or for another. 



CHAPTER VIII. 



Of the Nature and correct Use of the Excrements of Animals con- 
sidered as Manure; the Mode of its Action and Preservation. — 
Bone Dust, and dead Animal Matter. 

Calico printers for a long time have used the solid 
excrements of the cow in order to brighten and fasten col- 
ours on cotton cloth. This material appeared quite neces- 
sary, and its action was ascribed to some latent principle 
or material derivable from the living animal. But since 
the action of cow-dung was known to depend on ihe phos^ 
phates contained in it, it has been completely replaced by 
a more cleanly mixture of certain salts, of which the most 
prominent is phosphate of soda. 

So, similarly, in medicine, for many centuries the mode 
of action, or the active principle of all remedies, was veiled 
in obscurity. But now^ these principles have been present- 
ed to the world in an extremely active and concentiated 
form. The extraordinary efficacy of Peruvian bark in the 
cure of fever, is found to depend on the admixture of a 
minute quantity of a crystalline substance termed quinine, 
with the useless W'oody fibre 3 and the causes of the various 



98 PRODUCTIVE FARMING. 

effects of opium, in as many equally minute yet poweiful 
ini^rerlients in that clru(>;. The inhabitants of Savoy are 
much infested with the disease known among us as "Der- 
byshire neck." They have sprin^^s which are famous for 
its cure ; we derive benefit from the use of burnt sponge. 
Now, burnt sponge contains iodine ; and upon examina- 
tion these springs contain iodine in small quantities. The 
action of the sponge, or of the w^ater, must depend upon 
some definite cause common to both ; by ascertaining 
which we place the action and result completely at our 
command. 

Apply this reasoning to agricultural operations. One 
practical farmer applies, indiscriminately, any fertilizing- 
material to his land in any state ; another, more partial to 
what is technically termed " short muck," allows violent 
fermentation to reduce his mixture of straw and dung to 
one half its weight, — during which operation much gas- 
eous ammonia is disengaged and lost, which, if retained, 
or supplied to the soil, would have proved extremely ser- 
viceable. Both methods cannot be right in all cases. 

Besides the dissipation of gaseous matter when fer- 
mentation is pushed to the extreme, there is another disad- 
vantage in the loss of heat^ which, if excited in the soil 
instead of the dunghill, is useful in promoting the springing 
of the seed, and in assisting the plant in the first stage of 
its growth, when it is most feeble and most liable to dis- 
ease : and the decomposition of manure in the soil must be 
particularly favourable to the wheat crop, in preserving a 
genial temperature beneath the surface late in autumn and 
during winter. These views are in accordance with a 
well-known principle in chemistry, — that, in all cases of 
decomposition, substances combine much more readily at 
the moment of their disengagement than after they have 
been some time perfectly formed and set at liberty. And 
in fermentation beneath the soil, the fluid matter produced 
is applied instantly, even whilst it is warm, to the young 
organs of the rising plant; and, consequently, is more 



PRODUCTIVE FARMING. 99 

likely to be efficient, than in manure that has gone through 
the process, and of which all the principles have entered 
into new combinations. 

It is certainly a matter of inditference whether we em- 
ploy excrements, ashes, or bones, in carrying out the 
principle of restoring to the soil those substances which 
have been taken from it by the previous crop. But, unless 
we know accurately what are those matters that have been 
actually removed, how is it possible to supply, otherwise 
than at random guess, the deficiency ? Fermented dung 
may be really useful, if wo nitrogen be demanded. A time 
will come when fields will be manured with saline solu- 
tions, with the ashes of burnt straw, or with salts of phos- 
phoric acid prepared in chemical manufactories, with as 
much certainty as now, in medicine, iodine cures the Der- 
byshire neck, or as quinine is substituted for the bulky 
powdered bark in fever. The same mixed mass of mate- 
rials may be useful in one state, less so in another and un- 
der other circumstances. A knowledge of the actual wants 
of the land, and of the exact composition of the proposed 
manure, is obviously necessary to enable the farmer to 
adapt the one to the other as a requisite and fitting remedy. 
If our object be the development of the seeds of plants, we 
know they contain nitrogen. Our manure then must be rich 
in this material. If by fermentation ammonia be formed in 
the manure, if it become dry, rotten, and nearly devoid of 
smell, having lost its previous heat; although it may cut 
better with the spade, we may be sure it has lost its nitio- 
gen, and, consequently, as far as our object is concerned, 
(the nutriment of the seed,) nearly lost its utility. The 
leaves, which by their action on the air nourish the stem 
and woody fibre; the roots, from which the leaves are 
formed ; in short, every part of the structure of a plant 
contains nitrogen in small and varying proportions. But 
the seeds are always rich in nitrogen. 

The most important object, then, of farming operations, 
at least as far as corn is concerned, is the supply of nitrogen 
to com plants in a state capable of being taken up by them, 



100 PRODUCTIVE FARMING. 

— the production, therefore, of manures containing the 
most of this element. Gypsum and nitrate of soda are as 
properly termed manures as I'aim-yard dung, bone-dust, or 
night soil ; but our present inquiry is, what class of sub- 
stances contain and yield to corn-plants most nitrogen? 
Nature, by the ordinary action of the atmosphere, furnishes 
as ujuch nitrogen to a plant as is necessary to its bare ex- 
istence. But plants do not exist for themselves alone : — 
the greater number of animals depend upon the vegetable 
Avorld for food ; and, by a wise adjustment of nature, plants 
have the remarkable power of converting, to a certain 
degree, all the nitrogen offered to them into nutriment for 
animals. We may furnish a plant with carbonic acid, and 
all the materials which it may require for its mere life; we 
may supply it with vegetable matter in a state of decay in 
the most abundant quantity ; but it will not attain complete 
development unless nitrogen be afforded to it by the supply 
of suitable manure: an herb will, indeed, be formed, but 
its seeds or grain will be imperfect and feeble. 

But when, with proper manure, we supply nitrogen in 
addition to what the plant would derive from natural sour- 
ces, we enable it to attract from the air the carbon which 
is necessary for its nutrition — that is, when that in the soil 
is not sufficient, we afford it a means of fixing the atmos- 
pheric carbon. 

There are two principal descriptions of manure, the 
beneficial agency of which is derivable almost exclusively 
from the large quantity of nitrogen they yield. 

These are tlie solid as well as fluid excrements of man 
and animals, their dung and urine. 

Urine is employed as manure either singly, in its liquid 
state, or with the fseces which are impregnated wiih it. It 
is the urine contained in night-soil which gives it the pro- 
perty of giving off ammonia, a propeity which the dis- 
charges from the bowels possess only in a very slight 
degree. Liquid manures act chiefly through the saline 
substances they hold in solution ; whild the solid manures, 
even of animal origin, contain insoluble matters which 



PRODUCTIVE FARMING. 101 

decay slowly in the soil, and there become useful only after 
a time. When we examine what substances we add to a 
soil by supplying it w^ith urine, we find that this liquid con- 
tains in solution ammoniacal salts, uric acid, (a substance 
itself containing much nitrogen,) and salts of phosphoric 
acid. 

Human urine consists in 1000 parts of 

Water, 932 

Urea, and other organic matters containing ni- > .^ 

trogen, 5 

Phosphates of ammonia, soda, lime, and mag- ) ^ 

nesia, ) 

Sulphates of soda and ammonia, ... 7 

Sal-ammoniac and common salt, ... 6 

1000 

In dung reservoirs, well constructed and protected from 
evaporation, the carbonate of ammonia, which forms in 
consequence of putrefaction, is retained in solution ; and 
when the putrefied urine is spread over the land, a part of 
this ammonia will escape with the water which evaporates. 
On account of the formation of carbonate of ammonia in 
putrid urine, it becomes alkaline, though naturally acid in 
its recent state; and when this carbonate of ammonia is 
lost by being volatilized in the air, (which happens in most 
cases,) the loss suffered is nearly equal to one half of the 
urine employed. So that, if we fix the ammonia, (by com- 
bining it with some acid which forms with it a compound 
not volatile,) we increase its action twofold. Now the 
carbonate of ammonia formed by the putrefaction of urine 
can he fixed, or deprived of its volatility, in many w^ays. 

If, for instance, a field be strewed with gypsum, or 
plaster of Paris, (in chemical language, sulphate of lime,) 
and then sprinkled with urine, or the drainings of the cow- 
shed, a double exchange or decomposition takes place. 
Sulphate of lime and carbonate of ammonia become con- 
verted into carbonate of lime (that is, chalk) and sulphate 
of ammonia ; and this because sulphuric acid has a greater 



102 PRODUCTIVE FARMING. 

affinity for ammonia than it has for lime. This sulphate of 
ammonia will remain in the soil — it will not evaporate. 

If a basin containing s})irit of salt, or muriatic acid, be 
left a few weeks in a close stable or privy, so that its sur- 
face is in free communication with the ammoniacal vapours 
that rise from below, crystals of muriate of ammonia, or 
common sal-ammoniac, will soon be visible, as an incrusta- 
tion about its edges. The ammonia that escapes in this 
way is not only entirely lost as far as vegetation is con- 
cerned ; it works also a slow but not less certain destruc- 
tion of the mortar and plaster of the building. For when 
in contact with the lime of the mortar, ammonia is con- 
verted into nitric acid, which gradually dissolves the lime. 
There are few schoolboys who have not picked out crys- 
tals of nitrate of potass, or saltpetre, from an old brick- 
wall ; and in this instance the atmosphere has yielded the 
ammonia. 

The offensive carbonate of ammonia in close stables is 
very injurious to the eyes and lungs of horses, as the army 
veterinary surgeons are well able to testify. They adopt 
measures to carry it off by ventilation and cleanliness. If 
the floors or stables of cow-sheds were strewed with com- 
mon gypsum, they would lose all their offensive and inju- 
rious smell, and none of the ammonia which forms could 
be lost, but would be retained in a condition serviceable as 
manure. This composition, swept from the stable floor, 
nearly constitutes what is sold under the denomination of 
urate. Manufacturers of this material state, that three or 
four hundred weight of urate form sufficient manure for an 
acre : a far more promising adventure for a practical farmer 
will be to go to some expense in saving his own liquid 
manure, and, after mixing it with burnt gypsum, to lay it 
abundantly upon his corn-lands. For, in this way, he may 
use as much gypsum as will absorb the whole of the urine. 
Now, in the manufacture o{ urate, the proportion of 10 
pounds is employed to every 7 gallons,— allowing the mix- 
ture, occasionally stirred, to stand some time, pounng off" 
the liquid^ and with it nearly all its saline contents, excej t 



PRODUCTIVE FARMING. 103 

the ammonia. Urate, therefore, can never present all the 
virtues of the urine — 100 pounds of urate containin^^ no 
greater weight of saline and organic matter than 10 gallons 
of urine. 

From the foregoing analysis it wouh! appear, that 1000 
pounds of human urine contain no less than 68 pounds of 
dry fertilizing matter of the richest quality, worth, at the 
present rate of selling artificial manures in this country, 
at least twenty shillings per hundred weight. Suppose 
we say that the liquid and solid excrements of one hu- 
man being amount on an average to a pound and a-half 
daily, then in one year they will amount to 547 pounds ; 
^vhich at the rate of three per cent, of contained nitro- 
gen, would yield sixteen pounds of that material for the 
land, a quantity sufficient to supply enough for eight 
hundred pounds of wheat, rye, or oats, or for nine hun- 
dred pounds of barley. As each person in reality voids at 
least one thousand pounds or pints of urine in a year, the 
national waste incurred in this form amounts, at the 
above valuation, to twelve shillings a-head upon every 
individual of the whole population of England and Wales. 
And if five tons of farm-yard manure per acre, added 
yearly, will keep a farm in good order, four hundred 
weight of the solid matter of urine would probably have 
an equal effect — in other words, the excrements of a a sin- 
gle individual, are more than sufficient to yield the requi- 
site nitrogen to an acre of land, in order to enable it 
(with the assistance of the nitrogen absorbed naturally from 
the atmosphere) to produce the richest possible yearly 
crop. Every town and farm might thus supply itself 
with the manure, which, besides containing the most nitro- 
gen, contains also the most phosphates ; and if an alterna- 
tion of the crops were adopted, they would be most abun- 
dant. By using at the same time bones and wood ashes, 
the excrements of animals might be completely dispensed 
with. So that artificial, mineral, or chemical manures are 
no imperfect substitutes, if applied judiciously. 

The urine alone discharged into rivers or sew^ers by a 



104 PRODUCTIVE FARMINa 

town population of 10,000 inhabitants wcmld supply ma- 
nure to a farm of 1500 acres, yielding a return of 4,500 
quarters of corn, or an equivolent produce of other crops. 
The powerful agency of urine as a manure is well known 
on the Continent, and the Chinese justly consider it as 
invaluable ; and they are the oldest as well as the best 
agriculturists in the v^rorld. Indeed so much value is at- 
tached to human excrements by the Chinese, that the 
laws of the country forbid that any of them should be 
thrown away ; and reservoirs are placed in every house, 
where they are collected with the utmost care. jYo other 
kind of manure is used for their corn-fields. 

Human urine contains a greater variety of constituents 
than any other species examined. Urea, uric acid, and 
another acid similar to it in nature called rosacic acid, acetic 
acid, albumen, gelatine, a resinous matter, and its various 
salts, are all valuable to the land, inasmuch as from the 
land they or their elements have been originally derived. 
The urine of animals that feed exclusively on flesh contains 
more animal matter, and consequently more nitrogen, than 
that of vegetable feeders, whence it is more apt to run into 
the putrefactive process and disengage ammonia. In pro- 
portion as there are more gelatine and albumen in urine, so 
in proportion does it putrefy more rapidly. Thus, then, all 
urine contains the essential elements of vegetables in a 
state of solution ; and that will be the best for manure 
which contains most albumen, gelatine, and urea. Putrid 
urine abounds in ammoniacal salts, and is only less active 
as a manure than fresh urine, because of the portion of 
ammonia which is continually exhaling into the atmos- 
phere. 

As to the urine of cattle, it contains less water than that 
of man, varying with the kind of food on which the animal 
is fed. A cow will secrete and discharge from two thou- 
sand to three thousand gallons of urine a year ; and this 
quantity will contain at least from 1200 to 1500 pounds of 
dry solid saline matters, worth from ten to twelve pounds 
sterling monies of the realm. Even in the liquid state, the 



PRODUCTIVE FARMING. 105 

urine of one cow, collected and preserved as it is in Flan- 
ders, is valued in that country at about £2 a-year. Any prac- 
tical English farmer may easily make the calculation for 
himself, how much real w^ealth is lost in his own farm- 
yard, how much of the natural means of reproductive indus- 
try passes into his drains or evaporates in the air. 

The urine of the cow is particularly rich in salts of pot- 
ash, but contains very little soda. The urine of swnne con- 
tains a large quantity of the phosphates of ammonia and 
magnesia. That of the horse contains less nitrogen and 
phosphates than that of man. 

The fertilizing powers o^ animal manures, w^iether fluid 
or solid, is dependent, like that of the soil itself, upon the 
happy admixture of a great number, if not of all, those 
substances which are required by plants in the universal 
cultivation they receive from the industry and skill of man, 
more especially upon the large proportion of nitrogen they 
contain. The amount of this latter material affords the 
readiest test by which their agricultural value, compared 
with other matters and with that of each other, can be tol- 
erably well estimated. 

Ordinary farm-yard manure, in its recent state, contains 
a given proportion of nitrogen ; but fifteen pounds of blood 
would yield as much nitrogen as one hundred pounds of 
farm-yard compost. If dried blood were taken, four pounds 
would be sufficient ; three pounds of feathers, three of horn 
shavings, five of pigeon's dung, or even two and a half of 
woollen rags, would counterpoise one hundred of the first 
named material. Sixteen w^ould be the equivalent number 
for the urine of the horse, ninety-one that of the cow, sev- 
enty-three for horse-dung, one hundred and twenty -five for 
cow-dung ; while the mixed excrements of either animals 
would correspond wath the fact that the discharges of the 
cow offer no resemblance to those of the horse. 

Besides their general relative value, namely, as to the 
proportions of nitrogen they contain, the above matters 
have a further special value, dependent upon the diversity 
of saline and other organic matters which they severally 

6 



106 PRODUCTIVE FARMLNG. 

contain. Thus, three of dried flesh are equal to five of 
pigeons' dung, as far as nitrogen is concerned ; but then 
pigeons' dung contains a quantity of bone, earth, and saline 
matter, scarcely present in the former. Hence, the dung 
of fowls will benefit vegetation in some instances where 
even horse-flesh, ortlinarily regarded as a strong manure, 
would fail. And why ? Evidently because, if saline mat- 
ters are deficient in the soil, an excessive supply of nitro- 
gen will not serve as their substitute. So the liquid ex- 
cretions contain much important sali7}e matter not present 
in solid dung, nor in such substances as horn, hair, or wool; 
and therefore each must be capable of exercising its own 
peculiar influence, and be comparatively useless if deficient 
of those matters which are also found wanting, delicient, 
yet necessary in the soil. This affords the reason why no 
one manure can long answer on the same land ; it can only 
supply the materials it contains. When all the silicate of 
potash in corn-fields is exhausted, urine will not, cannot, 
supply the deficiency, because it contains no silicate of 
potash. So long as the land remained rich in this material, 
urine or blood would supply the requisite nitrogen. Hence, 
in all ages and countries, the habit of employing inixed 
manures and artificial composts has been universally dif- 
fused. What is wanting is a rpore accurate knowledge of 
the precise deficiency at any given moment, and a conse- 
quent saving of capital from unnecessary waste, together 
with an immense increase in fertility, as the reward of so 
accurate an adaptation of means and ends. The know- 
ledge of a disease is essential to the correct application of 
a remedy. 

A high degree of culture requires an increased supply 
of manure. With its abundance, the produce in corn and 
cattle will augment, but must diminish with its deficiency. 

From the foregoing remarks, it must be evident, that the 
greatest value should be attached to the liquid excrements 
of man and animals when a manure is desired which shall 
supply nitrogen to the soil. And as nitrogen is seldom 
wanted alone, — and as, generally, in practice, both liquid 



PRODUCTIVE FARMING. 107 

and solid excrements are found associated, containing, be- 
sides nitrogen, many other essential and invaluable ingredi- 
ents, — too much care cannot be taken, not only in preserving 
them, but, which is equally important, in securing to the 
land the full value of their operation, by applying them, 
in the best possible condition, for the development of their 
powers. 

We have already alluded to the loss sustained by the 
fermentation of dung-heaps. As we observed, in an earlier 
section, when it is considered that, with every jiound of 
ammonia which evaporates, a loss of sixty 'pounds of corn 
is sustained, and that, with every pound of urine, a pound 
of wheat might be produced, the indifference with which 
liquid refuse is allowed to run to waste is quite incompre- 
hensible. That it should be allowed to expend its ammo- 
nia by fermentation in the dung-heap, and evaporation into 
the atmosphere, is ascribable solely to ignorance of the 
elementary outlines of that science which hitherto the prac- 
tical farmer has thought it no disgrace, but rather an honour 
to publish, glorying in his utter disregard of all bookish 
knowledge, and substituting his own notions of wasteful 
and vague experience, for the calm deductions of sound 
and rational investigation. In most places, only the solid 
excrements impregnated with the liquid are used ; and the 
dunghills containing them are protected neither from eva- 
poration, nor from rain. The solid excrements contain the 
insoluble, the liquid excrements all the soluble phosphates ; 
and the latter contain, likewise, all the potash which ex- 
isted as organic salts in the plants consumed by the ani- 
mals which feed upon them. 

It is by no means difficult to prevent the destructive 
fermentation and heating of farm-yard compost. The sur- 
face should be defended from the oxygen of the atmos- 
phere. A compact marl, or a tenacious clay, offers the 
best protection against the air ; and before the dung is cov- 
ered over, or, as it were, sealed up, it should be dried as 
much as possible. If the dung be found at any time to 
heat strongly, it should be turned over, and cooled by ex- 



108 PRODUCTIVE FARMING. 

posure to air. Watering dung-hills is sometimes recom- 
mended for checking the process of putrefaction, and 
the consequent escape of ammonia ; but this practice is 
not consistent with correct chemistry. It may cool the 
dung for a short time ; but moisture is a principal agent in 
all processes of decomposition. Water, or moisture, is as 
necessary to the change as air ; and to supply it to reeking 
dung, is to supply an agent which will hasten its decay. 

If a thermometer, plunged into the dung, does not rise 
much above blood-heat, there is little danger of the escape 
of ammonia. When a piece of paper, moistened with 
spirit of salt, or muriatic acid, held over the steams arising 
from a dung-hill, gives dense fumes, it is a certain test that 
decomposition is going too far ; for this indicates that am- 
monia is not only formed, but is escaping to unite with the 
acid in the shape of sal-ammoniac. 

When dung is to be preserved for any time, the situa- 
tion in which it is kept is of importance. It should, if 
possible, be defended from the sun. To preserve it under 
sheds w^ould be of great use, or to make the site of a dung- 
hill on the north side of a wall. The floor on which the 
dung is heaped, should, if possible, be paved with flat 
stones ; and there should be a httle inclination from each side 
towards the centre, in which there should be drains, con- 
nected with a small well, furnished with a pump, by w^hich 
any fluid matter may be collected for the use of the land. 
It too often happens, that a heavy, thick, extractive fluid is 
suffered to drain away from the dung-hill, so as to be en- 
tirely lost to the farm. 

JVight-soil, it is well known, is a very powerful manure, 
and very liable to decompose. Human excrements differ 
in their composition, but always abound in nitrogen, hydro- 
gen, carbon, and oxygen. From the analysis of Berzelius, 
it appears that a part of it is always soluble in water; and 
in whatever state it is used, whether recent or decomposed, 
it supplies abundant food to plants. But this affords no 
excuse for its misapplication in any other condition than 
that which is most profitable. It varies, no doubt, in rich- 



PRODUCTIVE FARMING. 109 

ness with the food of the inhabitants of each district, — 
chiefly with the quantity of animal food they consume, — • 
but, when dry, no other solid manure, w^eight for weight, 
can probably be compared with it in general efficacy. 
The soluble and saline matters it contains are made up from 
the constituents of the food w^e eat ; of course, it contains 
most of those elementary substances which are necessary 
to the growth of the plants on which we live. The disa- 
greeable smell of night-soil may be destroyed by quick 
lime. If exposed to the air in thin layers strew^ed over 
with lime, in fine weather, it speedily dries, is easily pul- 
verized, and, in this state, may be used in the same manner 
as rape-cake, and delivered into the furrow w^ith the seed. 
If ni2:ht-soil be treated in a proper manner, so as to re- 
move the moisture it contains, without permitting the es- 
cape of its ammonia, it may be put into such a form as 
will allow it to be transported even to great distances. This 
is already attempted in many places ; and the preparation 
of human excrements for exportation constitutes not an un- 
important branch of industry. But the manner in which this 
is done, is not always the most judicious. In Paris, the ex- 
crements are preserved in the houses in open casks, from 
w^hich they are collected and placed in deep pits at Mont- 
fau^on ; but they are not sold till they have attained a cer- 
tain degree of dryness by evaporation in the air. But 
whilst lying inthe receptacles appropriated for them in the 
houses, the greatest part of their urea is converted into 
carbonate of ammonia ; lactate and phosphate of ammonia 
are also formed, and the vegetable matters contained in them 
putrefy; all their sulphates are decomposed, whilst their sul- 
phur forms sulphuretted hydrogen. The mass, when dried 
by exposure to the air, has lost more than half of the nitro- 
gen which the excrements originally contained ; for the 
ammonia escapes into the atmosphere along with the water 
which evaporates; and the residue now consists principally 
of phosphate and lactate of ammonia, and small quantities 
of urate of magnesia and fatty matter. Nevertheless, it is 
still a very powerful manure ; but its value as such would 



110 PRODUCTIVE FARMING. 

be twice or four times as great, if the excrements, before 
being dried, were neutralized with a cheap mineral acid. 

In other manufactories of manure, the excrements, whilst 
still soft, are mixed with the ashes of wood, or with earth ; 
both of which substances contain a large quantity of caustic 
lime, by means of w4iich a complete expulsion of all their 
ammonia is effected, and they are completely deprived of 
smell. But such a residue applied as manure, can act only 
by the phosphates which it still contains ; for all the am- 
moniacal salts have been decomposed, and their ammonia 
expelled. In London, night-soil is dried with various 
mixtures ; while, in other of our large towns, what is 
called " animalized charcoal " is prepared by mixing and 
drying night-soil with gypsum and ordinary wood charcoal 
in" fine powder. In all cases, the excrements of human 
beings contain more nitrogen than those of any other 
animal. Berzelius obtained, by the burning of 100 parts 
of dried excrements, 15 parts of ashes, principally com- 
posed of the phosphates of lime and magnesia. 

It is quite certain that the vegetable constituents of the 
excrements with which we manure our fields, cannot be 
entirely without influence upon the growth of the crops on 
them ; for they will decay, and thus furnish carbonic acid 
to the young plants. But it cannot be imagined that their 
influence is very great, when it is considered that a good 
soil is manured only once every six or seven years ; that 
the quantity of carbon thus given to the land corresponds 
only to 5 per cent, of what is removed in the form of herbs, 
straw, or grain ; and further, that the rain-water received by 
a soil contains much more carbon in the form of carbonic 
acid than these vegetable constituents of animal excrement. 
The 'peculiar action, then, of solid, as opposed to fluid, 
animal excrements, is limited to their mor^amc constituents, 
rather than to the presence of the partially changed vege- 
table or organized matter which they contain. Horse 
dung contains a large proportion of such partially altered 
vegetable matter ; and the reason why night-soil is a more 
powerful manure, is that, relatively, it contains less vege- 



PRODUCTIVE FARMING. Ill 

table matter, while nitrogen is more abundant ; and this, 
principally, because its weight is materially made up by 
the liquid excrement, or urine, always forming part of its 
composition. Now, urine easily putrefies, and yields am- 
monia largely; and this because of its containing more 
animal matter than is contained in dung. A horse lives 
exclusively on vegetables ; and 100 pounds of the urine of 
a healthy man, (living, of course, partially upon flesh, and 
partly upon those seeds and parts of plants containing 
nitrogen, in quantity,) will yield as much nitrogen as 1300 
pounds of fresh horse-dung, or 600 of cow-dung. We 
cannot ascribe much of the power of the excrements of 
cattle, sheep, and horses, to the nitrogen which they con- 
tain, for the quantity derivable from these vegetable feeders 
is too minute. The restoration of inorganic matter to thd 
land, is the cAie/" value arising from the application of the 
dung of cattle. A certain amount of inorganic matter is 
removed with every crop. If we manure that land with 
the dung of the cow or sheep, we restore to the surface 
silicate of potash, and some salts of phosphoric acid. If 
we use horse-dung, we supply, chiefly, phosphate of mag- 
nesia and silcate of potash. In the straw which has 
served as litter, we add a further quantity of silicate of 
potash, and phosphates, which, if the straw be already 
putrefied, are exactly in the same state as before they 
formed part of the crop w^hich yielded them. 

But, if we use human excrements, in addition to the 
phosphates of hme and magnesia, we supply a larger pro- 
portion of compounds of nitrogen, essential to the develop- 
ment of those parts of plants upon which human beings are 
accustomed to feed : and, by a WMse ordination, corn-plants 
are found associated with human dwellings, — in other 
words, the family of man having selected such spots on the 
earth's surface, as are fltted for the growth of corn, animal 
manure is always at hand in quantity for its artificial culti- 
vation ; thus restoring, through the feculent discharges of 
man and animals resident on the spot, precisely those mate- 
rials which the process of grow^th has removed from the soil. 



112 PRODUCTIVE FARMING. 

Cow-dung is not incorrectly said to be "cold:'^ so 
much of the sahne, nutritive, and other organic matters 
from the cow, pass off almost exclusively with her urine, 
that her dung does not readily heat and run into putrefac- 
tion. Still, mixed with other manures, or well diffused 
through the soil, its vegetable matter is not useless. It 
loses more than any other similar substance in drying. The 
dung of pigs is soft and cold, like that of the cow; contain- 
ing, like it, nearly 80 per cent of water. Mixed with other 
manures, it may be applied to any crop ; but is of very 
variable quality, owing to the variety of food of the animal. 

The horse is fed, generally, on less liquid food, less 
succulent and watery than that of oxen. He discharges 
less urine, — hence his dung is richer in animalized matter : 
or, adopting the figurative language of the farmer, it is 
hotter, and, indeed, runs more readily into the putrefactive 
fermentation. 

If the solid excrements of animals are chiefly valuable 
for the saline, earthy, and inorganic constituents they re- 
store to the soil which has yielded them, it will be readily 
inferred, that instead of dung or night-soil, other substan- 
ces, containing their peculiar ingredients, may be substi- 
tuted. One hundred tons of fresh horse-dung, if dried, 
would leave only from 25 to 30 tons of solid matter, the 
rest being only water ; and if this dried matter (itself only 
one-fourth of the original weight) were burnt, so as to 
decompose its vegetable ingredients, we should obtain, per- 
haps, 10 per cent, of really useful saline and earthy matters, 
(one-fortieth of the original weight,) according to the rich- 
ness or poverty of the food the horse had taken. 

Now, this minute proportion of saline and earthy mat- 
ters, and its relative quantity, in the various kinds of dung 
or excrement, forms, evidently, the chief topic of interest to 
which our attention should be directed ; inasmuch as what 
is left upon such examination and analysis, is exactly what 
has made up the component inorganic parts of the hay, 
straw, grass, or oats, on which the animal has been fed; 
or, in other words, exactly what has been removed from the 



PRODUCTIVE FARMING. Il3 

soil, and requires to be replaced, if the next crop is to equal 
the last. If our object is increased fertility, more must be 
added than has been taken away. Hay, straw, and oats, 
formed (for illustration' sake) the food of a horse. Their 
principal constituents are the phosphates of lime and mag- 
nesia, carbonate of lime, and silicate of potash ; the first 
three of these preponderated in the corn, the latter in the 
hay, and these, removed from the soil with the crop, are 
precisely the saline matters which would be found in the 
excrement of the animal for whose support that crop was 
intended. 

In order, then, to atone for the absence of that excre- 
ment which derives its value from the soil which has pro- 
duced it, and for which it is peculiarly fitted, as containing 
what that soil has lost, the ashes oficood or hones may often 
be judiciously substituted ; and for this reason ; wood- 
ashes contain silicate of potash, exactly in the same propor- 
tion as that salt is found to exist in the straw of the last 
crop; and as to hones, the greatest part of their bulk con- 
sists of the phosphates of lime and magnesia. Ashes ob- 
tained from various trees are of unequal value : those from 
oak-wood are the least, those from beech most serviceable. 
With every 100 pounds of the ashes of the beech spread over 
a soil, we furnish as much phosphates as 460 pounds of fresh 
night-soil could yield. But night-soil contains other useful 
matters besides phosphates ; hence the utility of mixed com- 
posts, as, evidently, the ashes of the beech would not alone 
secure fertility. 

Bone manure possesses still greater importance ^than 
wood ashes as a substitute for an indefinite and large sup- 
ply of animal excrement. The primary sources from. which 
the bones of animals are derived are, — the hay, straw, or 
other substances which they take as food. Now, bones 
contain more than half their weight of the phosphates of 
lime and magnesia ; and hay contains as much of these 
salts as wheat straw. It follows, then, that 8 pounds of 
bones contain as much phosphate of lime as 1000 pounds 
of hay or wheat straw; and 2 pounds of bones as much 

6* 



114 PRODUCTIVE FARMING. 

as is found in 1000 of the grain of wheat or oats. These 
numbers express pretty exactly the quantity of 'phosphates 
"which a soil yields annually on the growth of hay and corn. 
Upon every acre of land appropriated to the growth of 
wheat, clover, potatoes, or turnips, forty pounds of bone- 
dust will be found sufficient to furnish an adequate supply 
oi phosphates for three successive crops. 

To secure the best application of bones, they should be 
reduced to powder; and the more intimately they are mix- 
ed with the soil, the more easily are they taken up and 
assimilated. The most easy and practical mode of efiiscting 
this, is to pour over the bones, in powder, half their weight 
of sulphuric acid, (or oil of vitriol,) diluted with three or 
four parts of water; and after they have remained in con- 
tact for some time, say a fortnight, to add one hundred 
parts of w^ater, and sprinkle this mixture over the field be- 
fore the plough. Bones may be preserved unchanged, lor 
thousands of years, in dry, or even in moist soils, provided 
the access of rain be prevented, as is exemplified by the 
bones of animals, buried previous to the flood, lound in 
loam or gypsum ; the interior parts being protected by the 
exterior from the action of water. But they become warm 
when reduced to a fine powder ; and moistened bones 
generate heat, and enter into putrefaction ; — the gelatine 
which they contain is decomposed, and its nitrogen con- 
verted into carbonate of ammonia, and other ammoniacal 
salts, which are retained, in a great measure, by the powder 
itself. Bones burnt till quite white, and recently heated to 
redness, will absorb seven times their volume of ammonia- 
cal gas. The analysis of bone enables us to say, that while 
100 pounds of bone-dust add to the soil 33^of gelatine, the 
organized substance of horn, or as much organized matter 
as is contained in 300 or 400 pounds of blood or flesh, they 
add, at the same time, more than half their weight of iiior- 
ganic matter, lime, magnesia, soda, common salt, and phos- 
phoric acid, in combination with some of these ; — all ^of 
which, as we have seen, must be present in a fertile soil, 
since the plants require a certain supply of them all at 



PRODUCTIVE FARMING. 115 

every period of their growth, but more especially during 
the maturation of the straw and grain. These substances, 
like the inorganic matter of plants ploughed into the soil, 
may, and do exert a beneficial agency upon vegetation after 
all Ihe organized structure of such decaying plants is bro- 
ken up and destroyed. One hundred parts of dry bones 
contain 33 per cent, of dry gelatine, and are equivalent to 
250 parts of recent human urine. We do not speak now 
of the bone-dust w^hich remains after all the animal gela- 
tine is removed, in boiling them to extract size for the 
calico-printer. 

Horn is a still more powerful manure than bone, — that 
is to say, it contains a greater proportion of organized ani- 
mal matter. The peculiarity is, that horn, hair, and wool, 
as organized substances, are dry ; while blood and flesh 
contain from 80 to 90 per cent, their w^eight of water. 
Hence, a ton of horn-shavings, of hair, or of dry woollen 
rags, ought to enrich the soil with as much animal matter, 
(and consequently nitrogen,) as would be yielded by ten 
tons of blood. In consequence of this dryness, horn and 
wool decompose more slowly than blood ; and hence, the 
effect of soft animal matters is more immediate and appar- 
ent than that of hard and dry animal matters, the action 
of which is, nevertheless, stronger, and continues for a 
longer period. 

The refuse of the different manufactories of skin and 
leather form very useful animal manures; such as the shav- 
ings of the currier, furrier's clippings, and the offals of the 
tan-yard and of the glue-maker. The gelatine contained 
in every kind of skin is in a state fitted for its gradual de- 
composition ; and when buried in the soil, it lasts for a 
considerable time, and constantly affords a supply of nutri- 
tive matter to the plants in its neighbourhood. These ma- 
nures contain nitrogen as well as phosphates, and, conse- 
quently, are well fitted to aid the process of vegetable 
growth. 

From w^hat has been stated, we may arrive at the fol- 
lowing conclusions : — 



116 PRODUCTIVE FARMING. 

1. That fresh human urine yields nitrogen in greater 
abundance to vegetation than any other material of easy 
acquisition; and that the urine of animals is valuable for 
the same purpose, but not equally so. 

2. That the mixed excrements of man and animals 
yield, (if carefully preserved from further decomposition,) 
not only nitrogen, but other invaluable saline and earthy 
matters that have been already extracted in food from the 
soil. 

3. That animal substances which, like urine, flesh, and 
blood, decompose rapidly, are fitted to operate immediately 
and powerfully on vegetation. 

4. That d7'y animal substances, as horn, hair, or wool- 
len rags, decompose slowly, and (weight for weight) con- 
tain a greater quantity of organized as w'ell as unorganized 
materials, manifesting their influence it may be for several 
seasons. 

5. That bones, acting like horn, in so far as their ani- 
mal matter is concerned, and like it for a number of sea- 
sons more or less, according as they have been more or less 
finely crushed, may ameliorate the soil by their earthy mat- 
ter for a long period, (even if the jelly they contain have 
been injuriously removed by the size maker,) permanently 
improving the condition and adding to the natural capabili- 
ties of the land. 



CHAPTER IX. 



Of the comparative Value of Vegetable Manure, as contrasted with 
Animal Excrements. 

It may be asked, if the principal sources of the nitro- 
gen required for the artificial forcing of corn-plants be the 
feculent excretions of man and animals, — if the object be 
chiefly to replace in the soil those matters which have been 
abstracted with the previous crop, — how is it that such ex- 
crements more eflfectually restore those elements, than would 



PRODUCTIVE FARMING. 117 

occur if the ripe crop were ploughed into the soil ; in other 
words, how is it that dung and urine are richer in nitrogen 
than the food from which they are formed ? 

The answer is easy and obvious. The bulk of a vege- 
table is chiefly woody fibre or carbon. A horse lives ex- 
clusively upon vegetables, and discharges from his lungs, in 
breathing, a large portion of the carbon his food contains ; 
hence, what is left to be thrown off from his kidneys and bow- 
els, contains re/a^we/y a greater proportion of nitrogen which 
could only be otherwise feebly supplied to the soil from the 
rain-water of the atmosphere, while the air yields to the land 
carbon in abundance. Nearly the whole of the nitrogen con- 
tained in his food, (indeed, all beyond what is necessary for 
the wants of his own living system,) is thrown off in his 
urine and dung. In the food consumed, the carbon was to 
the nitrogen as 9 to 1 : in that which remains, after breath- 
ing has done its work, the carbon is to the nitrogen in the 
proportion of only 2 to 1. It is out of this residue, rich in 
nitrogen, that the several parts of animal bodies are built 
up. Warm-blooded animals with capacious lungs, double 
and triple their weight very rapidly after birth : they take 
in (as lambs or calves after separation from the parent) 
only vegetable food ; but the rapidity of its decomposition 
is the index or ratio of the rapidity of their growth. Their 
actions are lively; and the playful exertion of their 
muscles renders the decomposing play of the heart, and 
consequently of the lungs, more frequent than when fully 
grown. During their quick growth, they ahsorh all the 
nitrogen their food contains, while they throw off car- 
bon from the lungs. After growth is finished, they still 
throw off, in breathing, nearly all the carbon, while the re- 
sidual quantity of nitrogen (not wanted for the purposes of 
the living system) escapes in the dung and urine. The 
urine of a child would not, upon putrefaction, disengage the 
same quantity of ammonia as that of a full-grown man. 
Hence the reason why bodies can be nourished and built up 
upon food comparatively poor in nitrogen ; and yet not 
only do those same bodies contain nitrogen in quantity, but 



118 PRODUCTIVE FARMING. 

also their excretions are rich in the same element. The 
more nitrogen that is appropriated by growing cattle, the 
less will pass off into the fold-yard ; hence it is natural to 
expect that the manure, either liquid or solid, w^hich ac- 
cumulates where many young animals are fed, will not be 
so rich as that yielded by full-grown cattle, unless, by 
giving richer food to the young cattle than they actually 
require or can dispose of, the difference to the dung-heap 
be made up. A little acquaintance, then, with first princi- 
ples w^ill explain the seeming difficulty, how it is that the 
dung or urine of animals has a greater fertilizing power 
than even the whole weight of the food which they have 
consumed would have, if laid upon the soil. Its carbon 
has passed through the lungs of animals that have eaten it 
into the atmosphere : and the soil can always supply itself 
with sufficient carbon from the decomposition of the car- 
bonic acid of the air ; while its natural supply of nitrogen 
for the plants which grow on its surface is limited to the 
decomposition of the ammonia, and the evolution of nitro- 
gen from rain-water, — a quantity which, though sufficient 
for the sustenance of crabs, will not serve for apples ; and 
we must remember, that corn-plants are not in a state of 
nature, — wild oats or potatoes are widely different from the 
same plants under the care and culture of man. The differ- 
ence between a wild and a cultivated vegetable is not 
merely an increment of size, but the development of those 
parts which, though naturally containing nitrogen, contain, 
proportionally, far less than by artificial culture they may 
be compelled to take up. 

The doctrine of the proper application of manures from or- 
ganized substances offers an illustration of an important part 
of the economy of nature, and of the happy order in which 
it is arranged. The death and decay of animal substances 
tend to resolve organized forms into elementary constituents ; 
and the pernicious effluvia disengaged in the process seem to 
point out the propriety of burying them in the soil, where 
they are fitted to become the food of vegetables. The fermen- 
tation and putrefaction of organized substances in the free 



PRODUCTIVE FARMING. 119 

atmosphere are noxious processes : beneath the surface of 
the ground, they are salutary operations. In this case, the 
food of plants is prepared where it can be used, and that 
which would offend the senses and injure the health, if ex- 
posed, is converted, by gradual processes, into forms of 
beauty and of usefulness : the stinking gas is rendered a 
constituent of the perfume of a flower ; and what might be 
poison, swells the food of animals and man. 



CHAPTER X 



Of Manures of Mineral Origin, or Fossil and Artificial or Chemical 
Manures ; their Preparation, and the Manner in which they Act. — 
Of Lime in its Different States ; its Operation as a Manure. — 
Of Alkalies, and Common Salt, as to their Action upon the 
Land. 

From w^lat has been already said, a great variety of 
substances contribute to the growth of plants, and supply 
the materials of their nourishment. How matters that have 
once been living are in turn converted into the substance of 
other living things, may be comprehended ; but it is more 
difficult to understand those operations by which earthy and 
saline matters are taken up and consolidated in the fibre of 
vegetables. 

Sir Humphrey Davy, quoting the experiments of conti- 
nental chemists who had preceded him, states, on their 
authority, that different seeds sow^n in fine sand — flour of 
brimstone, or rust of iron, and supplied only with air and 
water, produced healthy plants, which by analysis yielded 
various earthy and saline matters, which either were not 
contained in the seeds or the material in which they grew ; 
and hence they and he concluded, that they must have been 
formed from air or water, in consequence of the agen- 
cies of the living organs of the plant. 

It would be impossible to pass this interesting fact, 



120 PRODUCTIVE FARMING. 

without observing how strikingly it confirms the views ad- 
vanced in the preceding pages as to the origin of nitrogen 
from the ammonia in rain-water. Sir Humphrey contends, 
from some subsequent experiments, that the atmosphere 
yields no saline matter to plants; but the existence of am- 
monia in rain-water, if not unknown to that distinguished 
chemist, w^as overlooked in his computation. 

The only substances that can, with propriety, be called 
fossil manures, and which are found unmixed with the re- 
mains of any organized beings, are certain alkaline earths, 
or alkalies, and their combinations. 

The only alkaline earths which have been hitherto ap- 
plied in this way, are lime and magnesia. Potash and so- 
da, the two fixed alkalies, are both used in certain of 
their chemical compounds, but never in a pure or caustic 
state. 

The most common form in which lime is found on the 
surface of the earth, is in a state of combination with car- 
bonic acid. We have already alluded to some of its che- 
mical properties in a previous section of this work. When 
common limestone is burnt in the kiln, the carbonic gas is 
driven oft" by the heat, and nothing remains but the pure 
caustic earth. If the fire have been very high, it approaches 
to one-half the weight of the stone; but, in common cases, 
limestones, if well dried before burning, do not lose much 
more than from 35 to 40 per cent., or from 7 parts to 8 out 
of 20. 

Very few limestones, or chalks, consist entirely of lime 
and carbonic acid. Statuary marble is nearly a pure 
carbonate of lime. When a limestone does not copiously 
effervesce in acids, and is yet sufficiently hard to scratch 
glass, it contains the earth of flint, and, probably, the earth 
of clay. When brownish or yellowish-red, the tinge, in 
all probability, depends upon the presence of iron. If not 
hard enough to scratch glass, if the stone effervesce slowly 
or but slightly with acids, and the solution have a milky 
appearance, — most probably magnesia is present. 

Before any opinion can be formed of the manner in 



PRODUCTIVE FARMING. 121 

which the different ingredients in limestones modify their 
properties, and their consequent action upon the soil, it will 
be necessary to consider the action of pure, or recently burnt 
caustic lime, when employed for agricultural purposes. 

Quicklime, — in its pure state, whether in powder, or 
dissolved in minute proportion, in water, — is directly inju- 
rious to 'plants. Grass may be certainly killed by sprinkling 
it with lune-water ; but since lime is a necessary ingredient 
in soils, and an useful addition in many cases, it evidently 
must be that its combination with carbonic acid — the state 
in which it is found naturally — is the circumstance which 
not merely renders it void of causticity, but so far alters its 
properties, as to exchange injury for advantage. Lime, if 
pure, and recently burnt, cannot long remain caustic, inas- 
much as it rapidly attracts sufficient carbonic acid from the 
atmosphere to reduce it to the state of chalk, or a carbonate; 
and it is a wise arrangement that it is so, — that it is never 
found, in nature, pure or free from this acid. 

Nevertheless, there are cases in which the application 
of caustic lime may be requisite. If it be mixed with any 
moist, fibrous, vegetable matter, there is a strong action 
between the lime and the vegetable fibrin : they form a kind 
of compost together, of which a part is usually soluble in 
water. By this kind of operation, lime renders matter 
which was comparatively inert, nutritive, or, at least, solu- 
ble ; and as charcoal and oxygen abound in all plants, the 
lime becomes at the same time usefully converted, even by 
their agency, into a carbonate. It is obvious, then, that 
the operation of quicklime, and that of marl or chalk, 
depends upon principles altogether different. Quicklime, 
in being applied to land, tends to bring any hard vegetable 
matter that it contains into a more rapid and easy state of 
decomposition ; while chalky forms of lime only add the 
necessary amount of this earth, so as to furnish the requisite 
supply to be absorbed as part of the inorganic structure of 
the plants which grow in that spot. Quicklime, when it 
becomes mild by exposure, acts in the same way as chalk, 



122 PRODUCTIVE FARMING. 

but, in the act of becoming mild, it prepares soluble out of 
insoluble matter. 

It is upon this circumstance that the operation of lime 
in the preparation for wheat crops depends, and its efficacy 
in fertilizing peats, and in brincring into a state of culti- 
vation all soils abounding in hard roots, dry fibres, or unde- 
composed and, therefore, useless vegetable matter. 

So, then, the solution of the question. Whether quick- 
lime ought to be applied to a soil ? depends upon the quan- 
tity of the undecomposed vegetable matter that soil con- 
tains; and the answer to the question. Whether marl, or 
any chalky carbonate of lime, ought to be applied 1 evi- 
dently depends upon whether the previous crops have 
exhausted the requisite quantity of lime necessary to form 
part of the inorganic material of the crop that is intended 
to be raised there. All soils are improved by mild lime, 
because each successive crop takes a portion of lime away. 
But, perhaps, one of the most important and influential 
agencies of lime in soil to which it is added, is to be found 
in its ready combination with 7iitric acid, which it assists 
in forming, from the facility with which it promotes the 
union of its already existing e]einenis, nitrogemnd oxygen. 
Nitrate of lime, which, by a series of inevitable actions, 
is produced in the decomposing soil, is very soluble in 
water: entering readily into the roots of plants, it forms the 
medium by which lime becomes part of a vegetable, (for, 
as before stated, the earths and alkalies never enter a 
plant in a pure, free, caustic, or uncombined state,) and 
producing upon growth effects precisely similar to those of 
the now weW-known nitrate of soda. Ploughing, harrow- 
ing, digging, and turning over the soil to the action of the 
air, is useful, chiefly, because it facilitates the more ready 
action of the atmosphere, indispensable to the formation of 
these nitrates. 

Besides pure, or caustic lime, and its carbonate, in the 
form of chalk or marl, the application of gypsum, or sul- 
phate OF LIME, — sometimes called alabaster, or plaster of 
Paris, — deserves a passing notice. Great difference of 



PRODUCTIVE FARMING. 123 

opinion has prevailed among agriculturists as to its use. 
Correct notions as to the nature of vegetable growth, an 
exact acquanitance with the constitution of plants intended 
to be raised upon a given locality, and the admitted neces- 
sity for an equally exact acquaintance with the existing 
condition of that soil, so as to adapt the one to the other, — 
in fact, a better knowledge of agricultural chemistry, — is 
all that alone is wanting, or can solve the variety of opinion 
as to its employment. Plaster of Paris has been advan- 
tageously used in England, and various testimonies as to its 
utility have been laid before the Board of Agriculture. 
Doubtlessly, if lime be deficient in a soil, though marl, or 
the carbonate, is more easily susceptible of action, the sul- 
phate or gypsum, which is less so, less easily decomposed, 
is better than none. Sulphuric acid has a stronger affinity 
for lime than carbonic acid can exert; hence, gypsum does 
not so readily enter into new combinations. It has been 
said, that sulphate of lime assists the putrefactive decom- 
position of animal substances, — that it hastens the evolution 
of ammonia, and the consequent development of nitrogen ; 
but the experiments of Sir Humphrey Davy disprove this 
view of the case. It would appear that peat-ashes natu- 
rally contain gypsum in abundance. These peat-ashes are 
used with advantage in some parts of the country, as a top- 
dressing for cultivated grasses, particularly clover; and, 
in examining the ashes of sainfoin and clover, they have 
been found to contain gypsum in quantity, proving that 
lime, in the form of a sulphate, is a necessary ingredient in 
the constitution of some vegetables. The practical deduc- 
tion from such investigations obviously is, that if clover be 
intended to be raised upon a soil deficient of lime, in the 
form of a sulphate, gypsum will not only constitute an ad- 
vantageous manure, but one that is absolutely. essential to 
the production of a vigorous, abundant, and healthy crop. 
Phosphate of lime is another combination of this earth 
with an acid. It forms the greatest part of calcined bones, 
of the utility and application of which we have already 
spoken. It exists in most excreraentitious substances, and 



124 PRODUCTIVE FARMING. 

is an essential constituent of the straw and grain of wheat, 
barley, oats, and rye, and likewise in beans, peas, and 
vetches. It exists in some places, in these islands, native, 
but only in small quantities. Phosphate of lime is general- 
ly conveyed to the land in the composition of other manure, 
and is absolutely necessary to corn crops. Bone-ashes, 
ground to powder, are useful on arable land that is defi- 
cient in lime, or its phosphate, especially if there be a su- 
perabundance of vegetable matter. If lime, or its phosphate, 
be the only deficient ingredient in the land, — if it already 
contain, or be at the same time supplied with animal ma- 
nure, yielding nitrogen, — then bone-dust may prove useful. 

Wood-ashes consist principally of the vegetable alkali, 
or potash, united to carbonic acid ; and as this alkali is 
found in almost all plants, it is not difficult to conceive that 
it may form an essential part of their organs. The general 
tendency of the alkalies applied as manure is, to supply the 
deficiency occasioned by what is removed with the previous 
crops. Wood-ash contains not only carbonate of potash, 
but also the sulphate of potash and silicate of potash ; 
hence its utility, as affording silex to wheat straw, — a ma- 
terial essential to its firmness and stability. These saline 
matters in wood-ash are all valuable, as supplying the ne- 
cessary inorganic constituents of plants ; and hence the ex- 
tensive use of wood-ash, as a manure, in every country 
where it can readily be procured. 

Peat-ashes vary, in constitution, with the kind of peat 
from which they have been prepared. They often contain 
traces of potash and soda, and generally a quantity of sul- 
phate and carbonate of lime, a trace of phosphate of lime, 
and much siliceous matter. In almost every country where 
peat abounds, the value of peat-ashes, as a manure, has 
been more or less generally recognised. 

Kelp. The ash left by the burning of sea-weed con- 
tains potash, soda, silica, sulphur, and several other of the 
inorganic constituents of plants, and is usefully and exten- 
sively employed in many districts near the sea, where plants 
naturally requiring these materials grow more luxuriantly 



PRODUCTIVE FARMING. 125 

than in more inland districts. Sea-weeds decompose with 
great rapidity when collected in heaps and laid upon the 
land. During their decay, they not only yield inorganic 
saline matter to the soil, but enrich it with an additional 
layer of vegetable mould. 

JVitrate of soda, and nitrate of 'potash or saltpetre. 
These substances have been much commended for their be- 
neficial action upon growing plants. They impart to the 
leaves a deeper green, and evidently quicken vegetable 
action : they are applied advantageously to grass and young 
corn, at the rate of a hundred weight of either to an acre. 
The nitric acid they contain yields the additional nitrogen 
beyond the quantity the plants can obtain by decompos- 
ing the ammonia contained in the rain that falls upon 
them ; at the same time, the other ingredient — potash or 
soda, as the case may be — is put within the reach of their 
roots, to be absorbed as an inorganic, yet necessary con- 
stituent. 

Commoji salt, muriate of soda, or, more correctly, a 
compound of the metal sodium with elementary chlorine, 
is undoubtedly indispensable to the fertility of many inland 
soils. It is not without design that the spray of the sea is 
allowed to be borne by the winds for many miles over the 
shore, so supplying an ample dressing of common salt to 
the land. A minute quantity is absolutely necessary to the 
healthy growth of all our cultivated crops, and most lands 
(in this island at least) contain a sufficient quantity of it 
for the purposes of vegetation. Common salt is found in 
every species of animal manure, and will be found most 
requisite in high situations exposed to the washing of heavy 
rains, which tend to remove the soluble alkaline matters 
from the soil. Much diversity of opinion has prevailed as 
to the utility of this substance. The Cheshire farmers plead 
in its favour. On the other hand, that salt in large quan- 
tities, renders land barren, was known long before any 
records of agricultural science existed. We read in Scrip- 
ture, that Abimelech took the city of Shechem, and sowed 
he land with salt, that the spot might be forever unfruit- 



126 PRODUCTIVE FARMING. 

ful. Pliny, a Latin historian, though he recommends giv- 
ing salt to cattle, yet affirms, that when strewed over land 
it renders it barren. But these form no argument against 
the proper application of it. There can be no question 
that salt, as well as many other similar mineral substances, 
are really useful to vegetation ; yet the intelligent agricul- 
turist ought not to be surprised to find, that a substance 
which is useful, because necessary and deficient in one in- 
stance, may be positively in excess, and consequently inju- 
rious, if added in another. He will try cautiously, and 
upon a small scale, whether this or that materia] seems 
fitted to answer his intention ; or, what is far better than 
blind hit-or-miss experiment, he will endeavour to ascer- 
tain the actual constitution of the soil, and not expect to 
grow wheat where there is no phosphate of lime or silicate 
of potash ; nor plants which thrive best near the sea, in a 
soil which he knows to be devoid of common salt. If salt 
be there, it is a needless and foolish waste to attempt to 
improve the land by adding more. If he has already bricks 
enough at hand, you must carry the builder mortar : more 
bricks will not supply the place of mortar. So, if the soil 
contain lime, or magnesia, or potash, in sufficient abun- 
dance for the wants of the plant it is our object artificially 
to force, it may still be deficient of other materials ; and 
here the skill and science of one man stand in beautiful 
contrast with the blundering, bungling guesses of another. 
At a meeting of the Chemical Society, a paper was lately 
read, containing a report of some experiments with saline 
manures containing nitrogen, conducted on the Manor Farm, 
Havering-atte-Bower, Essex, in the occupation of C. Hall, 
Esq., communicated by W. M. F. Chatterley, Esq. The exper- 
iments were suggested by the prevailing opinion, that the fer- 
tilizing power of some animal manures, and of the salts, 
nitre, (nitrate of potash,) nitrate of soda, and sulphate of 
ammonia, depend upon the proportion of nitrogen they 
contain. The salts mentioned are all, from their low price, 
within the reach of the farmer; and the quantity of the last 
thrown into the market is greatly increasing, from the ex- 



PRODUCTIVE FARMING. 127 

tension of the new mode of purifying coal-gas from its 
ammonia, by washing the gas with diluted sulphuric acid. 
The interest also of expeiiments with salts is greater than 
with mixed manures, both to the farmer, who, from the 
nature of the former substances, may depend upon their 
uniformity, and to the chemist, as their composition is ne- 
cessarily known to him. A field of wheat was chosen, 
which, in the latter end of April, 1842, presented a thin 
plant; the salts were top-dressed over the land by hand, 
on the 12th of May, and the crop mowed on the 10th of 
August. The soil was rather poor, consisting of a heavy 
clay upon a subsoil of the London clay. 1. No manure ; 
corn per acre 1413 lbs. 2. With 28 lbs. of sulphate of 
ammonia; corn, 1612 lbs. 3. With 140 lbs. of the same 
salt; corn, 1999 lbs. 4. With 112 lbs. of nitrate of soda ; 
corn, 1905 lbs. 5. With 1 12 lbs. of nitre ; corn, 1890 lbs. 
The increase in the straw was also considerable in all 
cases, except with the small proportion of sulphate of am- 
monia. The total increase in the four manured crops was 
per cent., in the order in which they were enumerated, — 
14.1,41.5, 34, and 33.5. The cost of the manure for the 
three last did not greatly differ, being 21s. 9d., 24s. 6d., 
27s. 6d. ; and the profit on the outlay was, with the small 
dose of sulphate of ammonia, 294 per cent. ; with the large 
dose, 212 per cent. ; with the nitrate of soda, 138 per cent. ; 
and with the nitrate of potash, 92 per cent. The princi- 
pal conclusions drawn by the author are, that the increase 
of nitrogen in the crop is greater than is accounted for by 
the nitrogen of the manures, showing that these manures 
have a stimulating effect, or enable the plants to draw ad- 
ditional nitrogenized food from the soil and atmosphere ; 
the considerable superiority of sulphate of ammonia over 
the other salts, and the greater proportional efficiency of a 
small, than of a large dose of that salt. The sulphate of 
ammonia costs 17s. per cwt. It appears best to apply this 
salt in the proportion of about 1 cwt. per acre, at three 
different dressings : the first quantity when the crop of 
wheat makes its spring growth, or if of oats, when about 



128 PRODUCTIVE FARMING. 

two inches above the ground ; the second quantity about 
a month afterwards ; and the third at the time of the for- 
mation of the ear. To meet the practical difficulty of dis- 
tributing so small a quantity as one-third of a hundredweight 
over an acre, about twice the quantity of common salt or 
of soot may be mixed with the ammoniacal salt. These, 
and most saline manures, when used as a top-dressing, 
should be supplied to the plant when dry, after a shower of 
rain, or during hazy weather. 

That which was true in the day of Sir Humprey Davy, 
when experimental agricultural chemistry was in its infancy, 
is equally true at the present moment. He observes that 
" much of the discordance of the evidence relating to the 
efficacy of saline substances depends upon the circumstance 
of their having been used in varying proportions, and in 
general in quantities much too large." That which is sal- 
utary and medicinal in moderate doses, not only may be, 
but is absolutely poisonous in another. 

Sir Humphrey made a number of experiments on the 
effects of different saline substances on barley and on 
grass growing in the same garden, the soil of which 
was a light sand, of which 100 parts were composed of 
60 parts of siliceous sand, and 24 parts finely-divided 
matter, consisting of 7 parts carbonate of lime, 12 parts 
alumina and silica, less than one part saline matter, prin- 
cipally common salt, with a trace of gypsum and magne- 
sia ; the remaining 16 parts were vegetable mould. The 
solutions of the saline substances were used twice a week, 
in the quantity of two ounces, on spots of grass and corn, 
sufficiently distant from each other to prevent any inter- 
ference of results. Several of the salts of potash, soda, 
magnesia and ammonia were experimentally and separ- 
ately employed. He found that in all cases, when the 
quantity of the salt equalled one-thirtieth part of the weight 
of the water, the effects w^ere injurious ; but least so with 
the salts of ammonia. When the quantities of the salts 
were one part in three hundred of the solution, or 1 pound 
to 300 pounds of water, the effects were different. Those 



PRODUCTIVE FARMING. 129 

spots watered with the solution of carbonate of ammonia 
were most luxuriant of all. This last result is what might 
be expected, (and it agrees well with the theoretic views 
of later chemists,) inasmuch as carbonate of ammonia is 
made up of carbon, oxygen, hydrogen, and nitrogen : all 
of which are essential to the supply of the additional quan- 
tities artificial plants require beyond that they can naturally 
obtain from the surrounding atmosphere. He observes that 
the solution of nitrate of ammonia seemed to be of no 
greater use than rain-water, and he attributes its failure to 
the circumstance of the acid being in excess. But Sir 
Humphrey was not aware that rain-water actually contains 
ammonia ; it was left to the genius of Liebeg, in our later 
day, to develope that discovery. 



CHAPTER XI. 



Of the Composition of Productive Soils, and of the Agency of the 
Elements in their Natural Formation, from the Rocks upon which 
they rest. 

We may now take it for granted that every' practical 
farmer will admit the position as proved, namely, that 
there must be an exact adaptation and fitness between the 
condition of any given soil and the plants intended to be 
raised upon it : and that, if this condition does not exist 
naturally, it not only may be, but must be, artificially 
remedied. 

At this stage of the inquiry, it will be our endeavour to 
anticipate further question, and to give an exact account of 
the chemical constitution of such soils as are known to be 
best suited to the cultivation and growth of green as well 
as corn crops. 

There are in existence as many varieties of soils as 
there are species of rocks exposed at the surface of the 

7 



130 PRODUCTIVE FARMING. 

earth. In fact, there are many more. Independently of 
the changes produced by cultivation and the exertions of 
human labour in tearing down and breaking up the sur- 
face, the materials of various layers have been mixed to- 
gether and carried from place to place by various great al- 
terations that, during a succession of ages, have been si- 
lently yet constantly carried forward in the system of our 
globe, together with the united agencies of air, water, 
and the varying alternations of summer's heat and the 
cold of winter. 

It may not be improper here to give a general descrip- 
tion of the geological constitution of Great Britain and Ire- 
land. It will be impossible to avoid the use of some names 
which scientific men have imposed upon the various rocks; 
and indeed, if we could offer the names by which they are 
vulgarly and popularly known in each district, it is proba- 
ble they would be equally unintelligible in distant parts of 
the country. From these rocks are formed, by the action 
of the elements, the various soils which support vegetation. 
Granite forms the great ridge of hills extending through 
Cornwall and Devonshire. Tiie highest rocks in Somer- 
setshire are limestone and grauwacke. The Malvern hills 
are composed of granite, sienite, and porphyry. The high- 
est mountains in Wales are chlorite, schist, or grauwacke. 
Granite occurs at Mount Sorrel in Leicestershire. The 
great range of mountains in Cumberland and Westmore- 
land are porphyry, chlorite, schist, and grauwacke ; but 
granite occurs at their western boundary. Throughout 
Scotland the most elevated rocks are granite, sienite, and 
micaceous schist. No true secondary formations are found 
in South Britain, and no basalt south of the Severn. The 
chalk district extends from the western part of Dorsetshire 
to the eastern coast of Norfolk. The coal formations 
abound in the district between Glamorganshire and Derby- 
shire, and likewise in the secondary strata of Yorkshire, 
Durham, Westmoreland, and Northumberland. Serpentine 
is found only in three places in Great Britain : in Cornwall, 
Aberdeenshire, and Ayrshire. Black and gray marble is 



PRODUCTIVE FARMING. 131 

found in Cornwall, and other coloured primary marbles 
exist in the neighbourhood of Plymouth. Coloured prima- 
ry marbles are abundant in Scotland. The principal coal 
formations in Scotland are in Dumbartonshire, Ayrshire, 
Fifeshire, and in Sutherland. Secondary limestone and 
sandstone are found in most of the low countries north of 
the Mendip hills. 

In Ireland there are five great associations of primary 
mountains ; the mountains of Morne in the county of Down ; 
the mountains of Donegal ; those of Mayo and Galway ; 
those of Wicklow and those of Kerry. Who does not re- 
member the words of the song, — 

" The Wicklow hills are very high, 
And so's the hill o' Howth, Sir." 

The rocks composing the first four of these mountain-chains 
are principally granite, gneiss, sienite, schist, and porphy- 
ry. The mountains of Kerry are chiefly constituted by 
granular quartz, and chlorite schist. Coloured marble is 
found near Killarney, and white marble on the west coast 
of Donegal. Limestone and sandstone are the common 
secondary rocks found south of Dublin. In Sligo, Roscom- 
mon, and Leltrim, limestone, sandstone, shale, iron-stone, 
and bituminous coal are found. The northern coast of Ire- 
land is principally basalt ; this rock commonly reposes on 
a white limestone, containing layers of flint, and the same 
fossils as chalk ; but it is considerably harder than that 
rock. The stone-coal of Ireland is principally found in Kil- 
kenny, associated with limestone and grauwacke. 

To attempt to class soils with scientific accuracy would 
be a needless labour ; the distinctions adopted by farmers 
are sufficient for our present purpose, particularly if some 
degree of exactitude be maintained in the application of 
terms. A full knowledge of modern geology is not neces- 
sary to enable a man to determine whether a field is best 
suited for arable or grazing purposes ; nor is it our inten- 
tion needlessly to employ the scientific appellations which 
would only puzzle because they are incomprehensible to 



132 PRODUCTIVE FARMING. 

minds unfamiliar with geological nomenclature. The ex- 
pression " a sandy soil,'^ is well understood ; but let it ne- 
ver be applied to any soil that does not contain at least 
three parts out of four of sand. Then, again, sandy soils 
that effervesce or give off carbonic acid, or fixed air, when 
vinegar or vitriol is poured upon them, should be distin- 
guished by the name of " sandy limestone soils,'' to mark 
them from sandy soils that contain silex or the earth of 
flint. The term " clayey soil,'' should not be applied to 
any land which contains less than one-sixth of an earthy 
matter not effervescing with acids; while the word " loam" 
should be limited to such soils as contain one-third of a 
smooth earthy matter, considerably effervescing with acids. 
A soil to be considered " peaty" ought to contain at least 
one-half of vegetable matter. 

Soils perform at least three functions in reference to 
vegetation. They serve as a basis in which plants may fix 
their roots and sustain themselves in the erect position — 
they are the medium through which the greater part of the 
inorganic matter of vegetables is supplied to them during 
their growth — and they allow many chemical changes to 
take place that are essential to a right preparation of the 
various kinds of food which are yielded to the growing 
plant. 

The best natural soils are those whence the materials 
have been derived from the breaking up and decomposition, 
not of one stratum or layer, but of many — divided minutely 
by air and water, and minutely blended together : and in 
improving soils by artificial additions, the farmer cannot do 
better than imitate the processes of nature. 

We have spoken of soils as consisting mostly of sandy 
lime, and clay, with certain saline and organic substances 
in smaller and varying proportions ; but the examination 
of the ashes of plants shows that a fertile soil must of ne- 
cessity contain an appreciable quantity of at least eleven 
diflferent substances, which in most cases exist in greater or 
less relative abundance in the ash of cultivated plants ; and 
of these the proportions are not by any means immaterial. 



PRODUCTIVE FARMING. 133. 

The labour requisite for the permanent improvement of land 
is repaid by correspondent advantage : the materials for 
the necessary adjustment are seldom far distant. If coarse 
sand be requisite, it is mostly or often found immediately over 
the chalky soil that needs it; and beds of sand and gravel are 
common below clay. Capital laid out in this way, secures 
for ever the productiveness and consequent value of the 
land. 

In ascertaining the composition of barren soils with a 
view to their productiveness, or of partially unproductive 
land, in order to its amendment, they should be compared 
with fertile soils in the same neighbourhood, and in similar 
situations ; as the difference of composition will, in most 
cases, indicate the proper methods of improvement. For 
instance, if on washing a portion of sterile soil it be found 
to contain largely any salt of iron, or any acid matter, it 
may be ameliorated with quicklime, which removes the 
sourness, or, in other words, combines with and neutralizes 
the acid. For though pure fresh burnt caustic hme is injuri- 
ous to vegetation, yet in combination with acids (as in 
chalk) it proves eminently serviceable. A soil, apparently of 
good texture, was put into the hands of Sir Humphrey Davy 
for examination, said to be remarkable for its unfitness for 
agricultural purposes; he found it contained sulphate of 
iron, or green copperas, and offered the obvious remedy 
of top-dressing with lime, which decomposes the sulphate. 
So if there be an excess of lime, in any form, in the soil, 
it may be removed by the application of sand or clay. 
Soils too abundant in sand are benefited by the use of clay 
or marl, or vegetable matter. To a field of light sand that 
had been much burnt up by a hot summer, the application 
of peat was recommended as a top-dressing ; it was attend- 
ed not only with immediate advantage, but the good effects 
were permanent. A deficiency of vegetable or animal 
matter is easily discoverable, and may as easily be supplied 
by manure. On the other hand, an excess of vegetable 
matter may be removed by paring and burning, or by the 
application of earthy materials. The effect of paring and 



134 FRODUCTIVC FARMING. 

burning is easily understood. The matted sods consist of 
a mixture of much vegetable with a comparatively small 
quantity of earthy matter ; when these are burned, only the 
ash of the plant is left, intimately mixed with the calcined 
earth. To strew this mixture over ihe exposed soil is much 
the same as dressing it with peat or wood-ashes, the bene- 
ficial effects of which upon vegetation are almost univer- 
sally recognised. From what has been already said, it will 
be easily evident, that the beneficial effect of the burnt ash is 
chiefly owing to the ready supply of inorganic and saline 
material it yields to the seeds which may afterwards be 
scattered there ; besides which, the roots of weeds and 
poorer grasses, if not exterminated by the paring, are so far 
injured as to lead to their death and subsequent decom- 
position. 

The improvement of peats or bogs, or marsh lands, must 
be preceded by draining, stagnant water being injurious to 
all the nutritive classes of plants. Soft black peats, when 
drained, are often made productive by the mere application 
of sand or clay as a top-dressing. The first step to be 
taken, in order to increase the fertility of nearly all the 
improvable lands in Great Britain, is to drain the7n. So 
long as they remain wet they will continue to be cold. 
Where too much water is present in the soil, that food of 
the plant which the soil supplies is so much diluted and 
weakened that the plant is of necessity scantily nourished. 
By the removal of the superfluous water, the soil crumbles, 
becomes less s>iff and tenacious, air and warmth gain ready 
access to the roots of the growing plant ; the access of air 
(and consequently of the carbonic acid which the atmos- 
phere freely supplies) being an essential element in the 
healthy growth of the most important vegetable produc- 
tions. Every one knows, that when water is applied to the 
bottom of a flower-pot full of soil, it will gradually find its 
way to the surface, however light that soil may be ; so in 
sandy soils or sub-soils in the open field. If water abound 
at the depth of a few feet, or if it so abound at certain sea- 
sons of the year, such water will rise to the surface ; and 



PRODUCTIVE FARMING. 135 

as the sun's heat causes it to dry off, more water will rise 

to supply its place. This attraction from beneath will 
always go on most strongly when the air is dry and warm, 
anfl so a double mischief will ensue: the soil will be kept 
cold and wet ; and instead of" a free passage of air down- 
wards about the growing roots, there will be established a 
constant current of water upwards. Of course, the remedy 
for all this is an efficient system of drainage. 

In genera], the soils which are made up of the most 
various materials are those called alluvial^ which have been 
formed from the depositions of floods and rivers. Many of 
these are extremely fertile. Soils consist of two parts; of 
an organic part, which can readily be burned away when 
the surface-soil is heated to redness ', and of an inorganic 
part, which remains fixed in the fire, consisting of earthy 
and saline substances; from which, if carbonic acid, or any 
elastic gas be present, it may, however, be driven by the 
heat. The organic part of soils is derived chiefly from the 
remains of vegetables and animals which have lived and 
died in and upon the soil, which have been spread over it 
by rivers and rains, or which have been adfled by the in- 
dustry of man for the purposes of increased fertility. 

This organic part varies much in quantity, as well as 
quality, in different soils. In peaty soils it is very abund- 
ant, as well as in some rich long cultivated lands. In 
general, it rarely amounts to one-fourth, or 25 per cent., 
even in our best arable lands. Good wheat soils contain 
often as little as eight parts in the hundred of organic ani- 
mal or vegetable matter : oats and rye will grow in a soil 
containing only 1^ per cent. ; and barley when only two or 
three parts per cent, are present. In very old pasture-lands, 
and in gardens, vegetable matter occasionally accumulates 
so as to be injurious, and overload the upper soil. This 
decaying vegetable, or animal matter, is the " humus" 
previously adverted to, and incorrectly supposed, before 
our day, to afford almost the sole nutriment essentially ne- 
cessary to growing plants. That living plants derive from 
the remains of their decayed predecessors the advantage of 



136 PRODUCTIVE FAEMING. 

being placed in contact with the inorganic or saline mate- 
rials those plants once contained, is not to be denied. But 
unless the whole crop were ploughed in, every year, this 
quantity would be exceedingly minute. The true value of 
green crops ploughed into the soil, or of decaying vegeta- 
ble matter, the " humus" of former writers, is the forma- 
tion of carbonic acid by the combination of decomposed 
carbonaceous or woody fibre with atmospheric oxygen ; 
thus supplying to the new and young roots carbon in a 
form susceptible of being taken up by them. 

The inorganic portion of any given soil is again divisi- 
ble into two portions — namely, that part which is soluble 
in water, and, therefore, in a state easily susceptible of be- 
ing taken up by the vessels of a growing vegetable, and of 
a further and much more bulky portion which is insoluble 
in water. The soluble portion consists of saline substances 
— the insoluble, of earthy materials. 

A single grain of saline matter in every pound of a 
soil a foot deep, is equal to 500 pounds in every acre, 
which is more than is carried off from the land in the course 
of forty years, supposing that the wheat and barley are 
sent to market, and the straw and green crops are regularly 
returned to the soil in the shape of manure. 

Sprengel, a German chemist, now^ at the head of the 
Prussian agricultural school, whose own taste, as well as 
his professional duty, have long directed his attention to 
scientific cultivation of the soil — has published an exact 
analysis of two varieties of 'productive soil, of which the 
following is an abstract : 

The first is a very fertile alluvial soil from East 
Friesland, formerly overflowed by the sea, but for sixty 
years cultivated with corn and pulse without manure. 

The second is a fertile soil near Gottingen, which pro- 
duces excellent crops of clover, pulse, rape, potatoes, and 
turnips ; the two last more especially uhen matured with 
gypsum. 

One thousand parts of each of these soils, after wash- 
ing, gave— 



PRODUCTIVE FARMING. 137 





No. 1. 


No. 2. 


Soluble saline matter, 


18 


1 


Fine earthy and organic matter, (clay) 


. 937 


839 


Siliceous sand, .... 


45 


160 



1000 1000 

The most striking distinction presented by these numbers is 
the large quantity of saline matter in the first variety. It 
consisted of common salt, muriate of potash, the sulphates 
of potash, gypsum, magnesia, and iron, with phosphate of 
soda, and other salts. The presence of this comparatively 
large quantity of these different saline substances, original- 
ly derived, no doubt, in great part from the sea, was proba- 
bly one reason why it could be so long cropped without 
manure. Its composition illustrates the truth of the state- 
ment, that a considerable supply of all the species of inor- 
ganic materials is necessary to render a soil eminently fer- 
tile. Not only does this soil contain a coniparatively large 
quantity of the soluble saline matters above enumerated, 
but it contains also 10 per cent, of organic matter, and 
some lime. The potash and soda, and the several acids, 
are also present in sufficient abundance. 

In the second instance, a fertile soil, but which could 
not dispense with manure, there is little soluble saline mat- 
ter ; and in the insoluble portion, only traces of potash, 
soda, and the important acids. It contains, also, 5 per 
cent, of organic matter, and 2 per cent, of hme, which 
smaller proportions, together with the deficiency oj alkalies, 
remove this soil from the most naturally fertile class, to that 
class which is susceptible in hands of ordinary skill, of be- 
ing brought to, and kept in a very productive condition. 

Sir Humphrey Davy examined some productive soils, 
which were very different in their composition. 

We will state the analysis of a few of them. 

Soil from Holkham, Norfolk, described as a " good 
turnip soil,'^ contained 8 parts out of 9 of siliceous sand ; 
that is, sand with flint earth, or silex : the remaining l-9th 
part consisted, in every 300 grains, oi — 

7* 



138 



PRODUCTIVE FARMING. 



Carbonate of lime, (chalk) 
Pure silex, .... 

Pure alumina, or the earth of clay, 
Oxide (rust) of iron. 
Vegetable, and other saline matter. 
Moisture and loss, 



63 grains. 

15 grains. 

11 grains. 

3 grains. 

5 grains. 

3 grains. 

100 



Thus the whole amount of organic matter in this instance 
is only 1 part in 200, or one-half per cent. ; a fact which, 
in itself, would demonstrate the fallacy of supposing that 
decomposed animal and vegetable matter in the soil form 
the exclusive supply to growing plants. 

In another instance, soil was taken from a field in Sus- 
sex, remarkable for its growth of flourishing oak trees. It 
consisted of 6 parts of sand, and 1 part of clay and finely- 
divided matter. One hundred grains of it yielded, in che- 
mical language — 



Of silica, (or silex) 

Of alumina, 

Carbonate of lime. 

Oxide of iron, 

Vegetable matter in a state of decomposition, 

Moisture and loss. 



54 grains. 
28 grains. 

3 grains. 

5 grains. 

4 grains. 

6 grains. 

100 



To wheat soils, the attention of the practical farmer will 
be most strongly directed. An excellent wheat soil from 
West Drayton, in Middlesex, yielded 3 parts in 5 of sili- 
ceous sand ; and the remaining two parts consisted of car- 
bonate of lime, silex, alumina, and a minute proportion of 
decomposing animal and vegetable remains. 

Of these soils, the last was by far the most, and the first, 
the least coherent in texture. In all cases, the constituent 
parts of the soil which give tenacity and stiffness, are the 
finely-divided portions ; and they possess this quality in 
proportion to the quantity of alumina (or earth of clay) 
they contain. A small quantity of this finely-divided mat- 
ter is sufliicient to fit a soil for the growth of turnips, or of 
barley, as turnips will grow (though it is not to be ex- 



PRODUCTIVE FARMING. 139 

pected they will thrive) on a soil containing 11 parts out of 
12 of sand. Sand in much greater proportion, or rather 
disproportion, produces sterility. So pure alumina, or pure 
silex, pure chalk, or magnesia, are incapable of supporting 
vegetation ; and no soil is fertile that contains 19 parts 
out of 20 of any one of the materials that have been men- 
tioned. 

Sprengel gives also the analysis of an unproductive soil 
from Luneburg. It contained, in 1000 parts — 

Soluble saline matter, .... 1 part. 

Fine earthy and organic matter, (clay) . . 599 parts. 

Siliceous sand, ..... 400 parts. 

1000 

This unfruitful soil, compared with the analysis given of 
the other two on a previous page, will be found to be the 
lightest of the three, containing 40 per cent, of sand. But 
this alone is not enough to account for its barrenness,- 
many light soils containing a larger proportion of sand, 
and yet sufficiently fertile. One thousand parts of its fine 
earthy matter contain 40 of organic matter instead of 97, 
— 778 of silica instead of 648, — 91 of alumina instead of 
57, — 4 of lime instead of 59, — 1 of magnesia instead of 
10, — 8 1 of oxide of iron instead of 6 1 ; while potash, soda, 
ammonia, chlorine, sulphuric acid, phosphoric acid, car- 
bonic acid, are entirely wanting ; such being the ingredi- 
ents and quantities in 1000 parts of the finer portion of the 
very fertile soil from East Friesland. The oxide of iron is 
in excess in the Luneburg barren soil ; there requires, there- 
fore, to be added, not only those substances of which it is 
destitute, but such other matters as shall prevent the inju- 
rious effects of the excessive proportion of iron. This 
illustration may serve to aid the practical farmer in com- 
prehending how far exact chemical analysis is fitted to 
throw light upon the capabilities of soils, and to direct ag- 
ricultural practice. The constitution of a soil, like the 
constitution of a horse, or a human being, requires to be 
known and understood, if we would prescribe otherwise 
than at random, expensively, unprofitably, or injuriously, 



140 PRODUCTIVE FARMING. 

either for the diseases of the one, or for the deficiencies of 
the other. 

The varying power of soils to absorb and retain water 
from the air, is much connected with their fertility. Sir 
Humphrey Davy has remarked upon this; and connecting 
his statement with the fact, that rain-water always con- 
tains ammonia, and, consequently, nitrogen, (as one of the 
elements of ammonia,) w-e can easily undeistand why it 
should be so. He observes, that " the soils which are most 
efficient in supplying a plant with water by absorption and 
retention from the atmosphere, are those in which there is 
a due mixture of sand, finely divided cloy and chalk, with 
some animal and vegetable matter; and yet so loose and 
light, as to allow the action of the air beneath the surface." 
Sand in excess destroys the requisite stiffness of the soil, 
but gives little absorbent power. 

The absorbe7it power of land is always greatest on the 
most fertile soils, thus affording one ready test of produc- 
tiveness. One thousand grains of soil, rendered perfectly 
dry by exposure to heat equal to that of boiling water, 
ought, by exposure to air, saturated with moisture, to gain 
in weight, at least 18 grains, or one-fiftieth ; so that the 
standard of fertility of soils for different plants must vary 
with the climate, (as well as the varying constitution of 
the soil itself,) and be particularly influenced by the quan- 
tity of rain that falls upon it. The power of soils to absorb 
moisture ought to be much greater in warm or dry coun- 
tries, than in cold, marshy places; and the quantity of clay 
they contain, greater. The inference is obvious : if defi- 
cient, it ought to be added. Soils, also, on the slope of 
a hill, ought to be more absorbent than in plains, or in the 
bottom of valleys. Their productiveness is also much in- 
fluenced by the nature of the sub-soil on which they rest; 
for, when soils are immediately situated upon a bed of rock 
or stone, they dry sooner by the sun's agency, than when 
the sub-soil is clay or marl. A prime cause of the fer- 
tility of the land in the moist climate of Ireland is, that 
happily the surface-soil rests upon a rocky substratum. A 



PRODUCTIVE FARMING. 141 

clay sub-soil will sometimes be of material advantage to a 
sandy upper-soil, inasmuch as it will retain the necessary 
moisture in such a manner as to be capable of supplying 
that lost by the earth above in consequence of evaporation. 
In the same way, a sandy or gravelly sub-soil often corrects 
the imperfection of too great a degree of absorbent power 
in the true soil. 

In devoting the different parts of an estate to the neces- 
sary crops, it is perfectly evident that no general principle 
can be laid down, except when all the circumstances of the 
nature, composition, and situation of the soil and sub-soil 
are accurately known. 

Whatever be the specific variety of the surface-soil, 
it will, of necessity, take its character from the prevalent 
substratum. In limestone countries, where the surface is a 
species of marl, the soil is often found only a few inches 
above the limestone, and its fertility is not impaired by the 
nearness of the rock : though, in a less absoi bent soil, this 
situation would occasion barrenness ; and tfie sandstone 
and limestone hills in Derbyshire and North Wales may be 
easily distinguished at a distance in summer by the different 
tints of their vegetation. The grass on the sandstone hills 
usually appears brown and parched, that on the limestone 
hills flourishing and green. 

Each locality will continue to present to the agricul- 
turist facilities for the cultivation of such vegetables 
as it is best fitted to raise, and for an indefinite period ; 
that is, until the exhaustion of its saline materials, its 
capability will continue. In clayey soils, it will continue 
longest ; because, as previously explained, all clays con- 
tain potash and soda. But even these in time are exhaust- 
ed. Air, water, and the changing temperature of the 
seasons, are at the same time preparing a remedy for the 
coming deficiency. Fresh surfaces of broken, crumbling 
rock are in a state of continual formation, exposing to the 
elements the saline treasures they contain. A period will 
arrive in the history of all soils, when, if their saline con- 
stituents are not artificially replaced, it will be necessary, 



142 PRODUCTIVE FARMING. 

either by deep ploughing, or other mechanical modes of 
breaking up and exposing the rock from which that soil 
has been formed, to obtain a fresh supply of soluble alka- 
lies. When the surface of a granite rock has been long 
subjected to the action of air and water, the lime and the 
potash it contains are acted on by both ; the felspar, mica, 
and quartz, of which that rock is compounded, are decom- 
posed. The felspar, which is, as it were, the cement of the 
stone, forms a fine day ; the mica, partially decomposed, 
mixes with it ?iS sand; and the undecomposed quartz appears 
as gravel, or coarse sand, of different degrees of fineness. 
Then, as soon as the smallest layer of earth is formed in 
this way, the seeds of mosses, and other imperfect vegeta- 
bles constantly floating in the atmosphere, and which have 
made that spot their resting-place, begin to vegetate : their 
annual reproduction and death furnishes a certain quantity 
of organizable matter, which mixes with the earthy mate- 
rials of the rock. In this improved soil, more perfect 
plants are capable of subsisting, the gradual process being, 
in truth, an epitome of the world's original creation. Fos- 
sil geology shows us that such was the process ; and that 
not until a soil was formed by the decay of reeds and 
mosses, was the earth's surface fitted to rear the stately 
oak. With every fresh disintegration of the surface, suc- 
cessive quantities of alkaline materials are presented to the 
growing vegetable. 



CHAPTER XII. ! 

! 
Of the Chemical Analysis of Soils, and how far this is practicable i 
by the Farmer. 

Enough has been already written to show what is es- : 
sential to the production of heavy crops, and to prove that 
a naturally good soil can be forced, or an inferior soil 
amended, only by the addition of such substances as are 
really requisite in each particular instance ; such adaptation, 
of course, pre-supposing an exact acquaintance with the 
nature of the land. 

But the practical farmer will anticipate the inquiry, 
How am I to arrive at this knowledge 1 I am no chemist: ! 
I can form some general notion of the composition of the 
soil which I cultivate; and, from experiments, (some of 
which have been fortunate, others confessedly expensive 
and unproductive,) I am enabled to say what seems to 
agree best with it. Is it necessary to employ a scientific 
chemist to analyze my wheat soils, or are the means of 
discovery within my own power? \ 

In reply to such very natural inquiries, — to a certain i 
extent, the means of analysis are within the reach of every I 
working farmer. Nevertheless it is perfectly true, that the 
management and tilling of the soil is a branch of practical 
chemistry ; and like the arts of dyeing, calico printing, or 
the smelting of metals, it may advance to a certain degree \ 
of perfection, — its present condition, (which has been sta- 
tionary and imperfect for many centuries,) — without the aid 
of science ; but it can only have its processes explained, and 
be led on to shorter, more economical, more productive, and 
perfect processes, by the aid of scientific principles. 

From the analysis of Davy and Sprengel, already given, 



144 PRODUCTLVE FARMING. 

of soils known to be enainently productive, (and two or three 
such iUustrations are as good as a thousand,) it is not diffi- 
cult to say of what materials a good wheat soil ought to 
consist. It is impossible to compare any given soil with 
these standards, unless we have a similar examination in- 
stituted ; and if it can be obtained from the hands of an 
able investigator, it is always very desirable, so much so as 
amply to repay the trifling expense. Chemistry has ren- 
dered many and great services to agriculture, and can render 
more : the two sciences ought not to be considered as hav- 
ing no relation to each other ; on the contrary, practical 
farming is only conducted on rational principles when di- 
rected by chemical science. Hitherto, it has fallen in with 
the humour or bias of only a few scientific men to enter 
upon such inquiries. Sir Humphrey Davy, the greatest 
chemist of his age, devoted his elTorts not only laboriously, 
but most usefully, to the prosecution of agricultural chem- 
istry ; and the recent views and discoveries of Liebeg, will 
do much to economize agricultural operations, as well as to 
direct the farmer to the easiest and shortest modes of doub- 
ling his crops. But generally, the appreciation of such ef- 
forts, on the part of learned men, has been so small — the 
reception of scientific results and suggestions by the farm- 
ing tenantry, so ungracious, that little wonder can exist that 
so many have quitted the field in disgust — that the majority 
of able chemists should studiously avoid it. Hence it has 
happened that in England, the analysis of soils has rarely 
been undertaken, except as a matter of professional busi- 
ness. Exact chemical analysis is a difficult art, one which 
demands much knowledge and skill in practice. It calls 
for both time and perseverance, if valuable, trustworthy, 
and minutely correct results are to be obtained. But it is 
only by aiming after such minutely correct results that chem- 
istry is likely to throw light on the peculiar properties of 
those soils, which,while they possess much general similarity 
in appearance, are yet found, in practice, to possess very 
different agricultural capabilities. 

Sir Humphrey Davy has given, with his usual precision, 



PRODUCTIVE FARMING. 



145 



very copious directions for the analysis of soils. But we 
have no hesitation in affirming, that few practical farmers 
are likely to attempt the task. Not that the requisite in- 
struments are either numerous or expensive, but that some 
familiarity with chemical operations is necessary ; and that 
little dependence could be placed upon results which, if in- 
correct, would mislead perhaps more widely than the merest 
p-uesses. Fortunately there are to be found men of ability 
in sufficient numbers to supply the requisite information ; 
and there is nothing more inconsistent in soliciting from a 
practical chemist a statement as to the actual composition 
of a given portion of soil, with a view to the supply of its 
deficiencies, than there is in employing a veterinary surgeon 
not only to give an opinion as to the nature of the ailment 
of a horse, but to advise the appropriate remedy. 

Undoubtedly, the utility and necessity of such interfer- 
ence or assistance may sound strangely— grate harshly 
upon the long-established usages of that class of English 
farmers with whom, unfortunately, mere exertion is a vir- 
tue, and skill or science a presumed apology for laziness. 
It would appear however, that in some agricultural dis- 
tricts, a spirit in most rational conformity with such com- 
binations of science with mere brute labour, is beginning 
to prevail. Early in the present year, a meeting of landed 
o-entry and farmers took place in Edinburgh, tor the ex- 
press purpose of forming an association /or the application 
of chemistry to agriculture ; a tolerably expressive indi- 
cation of the state of public feeling in Scotland, and one 
that, we trust, will be followed up by the organization of 
kindred institutions throughout the entire kingdom. The 
srreat and leading object of the association is to have a 
chemist of first-rate eminence, resident in Edinburgh, who, 
during the winter months, shall devote himself to analyzing 
such soils, manures, and other substances as may be sent 
him by farmers, and giving them advice regarding their 
value and usefulness. In summer he will visit different dis- 
tricts of the country, at the request of members of the as- 
sociation, and give a few lectures in the towns, or advice 



146 PRODUCTIVE FARMING. 

to individuals, regarding the system of management best 
suited to different soils. It is easy to see that all this will be 
attended with very great practical benefits to the country. 

We are aware, however, that there are persons who 
have a distrust of the aid to be had from chemistry in the 
delicate and refined processes of agriculture ; and to them 
we would address a few words. 

Now, the more recondite principles of vegetation are 
subjects on which neither chemist nor farmer will require 
to touch, Indeed, there will be no call made on the farm- 
ers ^ or j)ersons wishing the analysis, for any chemical 
knowledge. They are to submit limestones, bone-dust, 
guano, and manures of all kinds, marls, decaying rocks, 
and such like substances, to the chemist, and he is to pro- 
nounce on their value, and to point out their utility in 
reference to different soils, and for raising different crops. 
He will say, for example, whether the guano has been 
robbed of its ammonia, or the bone-dust of its gelatine, or 
whether the limestone be coloured with bituminous matter 
which will disappear with burning, or with iron which will 
not ; and then he will be able to say w^hat price the article 
ought to bear, and with what crops, on what soils, and at 
what periods it ought to be used. On the part of the per- 
son who sends the substance for analysis, it is plain that no 
knowledge of chemistry is required ; and even the chemist 
will not find his duty an arduous one. A few chemical 
tests, and an accurate balance, will be nearly all that he 
will require ; and he will have no occasion to approach 
those nice and subtile operations of nature, over which 
there certainly hangs a delicate and almost impenetrable 
veil. 

But the summer duties of the chemist will be even 
more important than the analysis which are to occupy his 
winter hours. During that season he will impart informa- 
tion on many of the more recent discoveries and improve- 
ments in practical agriculture; and already enough has been 
done to admit of his giving much valuable and curious 
information, whether in the form of lectures, or by commu- 



PRODUCTIVE FARMING. 147 

nicating with individuals. For example, the good effects 
of bone-dust, and of the phosphates generally, on peaty 
soils — of saline compounds for crops of hay on loams in 
trap districts — and of lime on granitic soils — may be men- 
tioned, and they admit of explanation. They are noticed 
here as a proof of the advancement already made in this 
kind of knowledge. But much yet remains to be done ; 
and besides giving information, it will be his duty no less 
to suggest experiments. He will give instructions to 
farmers to make trial of substances, the composition of 
which is known and determinate, on different soils, and 
\vilh a variety of crops, accurately noting the weight of 
the produce, both in its dry and moist state. And who does 
not see that such trials, made on a diversity of soils, (for in 
this respect the experiments will have the advantage over 
any which the chemist could make himself on an experi- 
mental farm,) will furnish him with results from which he 
may possibly draw some general principle. This, again, 
may point the way to other trials and new discoveries j and 
so on without limit. 

Need we say what will be the benefits of all this train- 
ing and experiment 1 In the first place, there will be a 
gain to the country at large in the increased productive- 
ness of the land ; and in this those will be the first to 
share who first know of the new methods that will give 
them crops at a lower cost than their neighbours. And, 
in the second place, a spirit of intelligence and inquiry can- 
not fail to be diffused among our farmers, of which it will 
be difficult to estimate the value. Instead of blindly fol- 
lowing in the old courses, they will have a pleasure in 
devising new ones, and will gradually raise themselves in 
the scale of being. And if it be true that even the mechan- 
ical arts will fall off, as DeTocqueville has admirably shown, 
if their principles are lost sight of, just as copies taken from 
copies decline at last from the original, much more will the 
fields of the farmer, changing in their composition with every 
crop that is taken from them, reward none at last but the 
intelligent and the skilful. 



CHAPTER XIII 



Of Advertised "Fertilizers" for the Soil. 

The publication of more scientific and enlarged views 
respecting the nature of vegetable growth, has led to the 
attempt to furnish mineral compositions to meet the supposed 
deficiency of saline matters in the soil. Their inventors 
secure the secret of each such composition by a patent -, in 
other instances they are left unprotected : nevertheless, it 
is a matter of no difficulty to say of what materials they 
chiefly consist. Now, there are such things as patent medi- 
cines, and, unquestionably, there is scarcely one of them 
that may not be good for some ailment or other. The mis- 
chief of such nostrums is, that they are recommended as 
universal specifics ; they will cure every thing. As any 
one may read of the last new fashionable pills, that they 
have stood the test of thousands of trials, ancl proved effica- 
cious in the removal of the direst and most diversified evils 
that can infest humanity ; so of these agricultural specifics, 
it is said that " their efficacy has been submitted to innu- 
merable tests since the ingredients were discovered ; by 
which trials their utility has been amply demonstrated in 
all instances." Now, this is saying too much. Macassar 
oil may cause a luxuriant growth of hair ; but rubbed upon 
a deal box, it will not convert it into a hair-trunk before 
the morning : and so a remedy, said to be universally \\sek\\, 
mostly proves (whether land or living creatures be the sub- 
ject of experiment) of little use in any instance. In some 
cases that have fallen under our own notice, the guano, 
which these mineral manures were intended to supersede, 
has proved a far more strongly-fertilizing substance. And 
if there had been no deficiency of the materials of which 
guano is exclusively composed, — if purely saline and earthy, 
rather than animal matter, had been wanting, the balance 



PRODUCTIVE FARMING. 149 

of recommendation would undoubtedly have turned the 
other way. All this shows that it is folly to add to a soil 
any other matters than precisely those which are exhausted 
or deficient; and that this can only rationally be attempted 
after a close examination of the materials of which that 
soil is composed. 

Let us suppose this is done, and that an artificial saline 
or mineral compost is judiciously and accurately put to- 
gether, either to meet the deficiency, or added to a tolerably 
good soil to increase its fertility. The advantages of its 
use are not overstated in a recent pamphlet. 

1st, It is cheap, compared with its value : a twenty 
shilling cask will supply an acre. 

2d, It is light and easily carried, when compared with 
carting manure. 

3(i, It is suitable for small holders who cannot aflford 
soiling, or keeping of cattle for making dung-heaps. 

Uh, It enables a tenant-at-will to take a good crop 
out of done-out land, if his landlord refuse to renew. 

bth, It furnishes to barren land such food for plants as 
had been deficient ; such defects of one or more substances 
being, in general, the cause of sterility. 

Qth, It enables the cultivator to extract ten times as 
much vegetable aliment for his plants from the soil, and 
from other manure, as they could otherwise, in most cases, 
yield. 

This is the language of one who has devoted much 
time, talent, and energy to the task of improving the soil ; 
and he believes there are no soils which may not be per- 
manently fertilized by the mineral compost which forms 
HIS invention. Thus he speaks of its powers. But bear- 
ing in mind the remarks we have already made, every 
practical farmer must advance upon his own responsibility 
in making trial of its capabilities ; the object of this work 
being, not the introduction of advertised artificial manures 
into the notice of the agricultural world, but rather the 
dissemination of those sound and rational views of the 



160 



PRODUCTIVE FARMING. 



necessary relations between practical farming and practi- 
cal SCIENCE, without which Agriculture must still lacr 
'behind the age, and, though the first and most importanl 
oi all arts, remain for ever stationary. 




THE END. 




'i^l i%^\ 



'M-^ 



